1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 #ifdef HAVE_conditional_execution
172 #ifndef REVERSE_CONDEXEC_PREDICATES_P
173 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
177 /* The obstack on which the flow graph components are allocated. */
179 struct obstack flow_obstack;
180 static char *flow_firstobj;
182 /* Number of basic blocks in the current function. */
186 /* Number of edges in the current function. */
190 /* The basic block array. */
192 varray_type basic_block_info;
194 /* The special entry and exit blocks. */
196 struct basic_block_def entry_exit_blocks[2]
199 NULL, /* head_tree */
203 NULL, /* local_set */
204 NULL, /* cond_local_set */
205 NULL, /* global_live_at_start */
206 NULL, /* global_live_at_end */
208 ENTRY_BLOCK, /* index */
216 NULL, /* head_tree */
220 NULL, /* local_set */
221 NULL, /* cond_local_set */
222 NULL, /* global_live_at_start */
223 NULL, /* global_live_at_end */
225 EXIT_BLOCK, /* index */
232 /* Nonzero if the second flow pass has completed. */
235 /* Maximum register number used in this function, plus one. */
239 /* Indexed by n, giving various register information */
241 varray_type reg_n_info;
243 /* Size of a regset for the current function,
244 in (1) bytes and (2) elements. */
249 /* Regset of regs live when calls to `setjmp'-like functions happen. */
250 /* ??? Does this exist only for the setjmp-clobbered warning message? */
252 regset regs_live_at_setjmp;
254 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
255 that have to go in the same hard reg.
256 The first two regs in the list are a pair, and the next two
257 are another pair, etc. */
260 /* Callback that determines if it's ok for a function to have no
261 noreturn attribute. */
262 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
264 /* Set of registers that may be eliminable. These are handled specially
265 in updating regs_ever_live. */
267 static HARD_REG_SET elim_reg_set;
269 /* The basic block structure for every insn, indexed by uid. */
271 varray_type basic_block_for_insn;
273 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
274 /* ??? Should probably be using LABEL_NUSES instead. It would take a
275 bit of surgery to be able to use or co-opt the routines in jump. */
277 static rtx label_value_list;
278 static rtx tail_recursion_label_list;
280 /* Holds information for tracking conditional register life information. */
281 struct reg_cond_life_info
283 /* A boolean expression of conditions under which a register is dead. */
285 /* Conditions under which a register is dead at the basic block end. */
288 /* A boolean expression of conditions under which a register has been
292 /* ??? Could store mask of bytes that are dead, so that we could finally
293 track lifetimes of multi-word registers accessed via subregs. */
296 /* For use in communicating between propagate_block and its subroutines.
297 Holds all information needed to compute life and def-use information. */
299 struct propagate_block_info
301 /* The basic block we're considering. */
304 /* Bit N is set if register N is conditionally or unconditionally live. */
307 /* Bit N is set if register N is set this insn. */
310 /* Element N is the next insn that uses (hard or pseudo) register N
311 within the current basic block; or zero, if there is no such insn. */
314 /* Contains a list of all the MEMs we are tracking for dead store
318 /* If non-null, record the set of registers set unconditionally in the
322 /* If non-null, record the set of registers set conditionally in the
324 regset cond_local_set;
326 #ifdef HAVE_conditional_execution
327 /* Indexed by register number, holds a reg_cond_life_info for each
328 register that is not unconditionally live or dead. */
329 splay_tree reg_cond_dead;
331 /* Bit N is set if register N is in an expression in reg_cond_dead. */
335 /* The length of mem_set_list. */
336 int mem_set_list_len;
338 /* Non-zero if the value of CC0 is live. */
341 /* Flags controling the set of information propagate_block collects. */
345 /* Maximum length of pbi->mem_set_list before we start dropping
346 new elements on the floor. */
347 #define MAX_MEM_SET_LIST_LEN 100
349 /* Store the data structures necessary for depth-first search. */
350 struct depth_first_search_dsS {
351 /* stack for backtracking during the algorithm */
354 /* number of edges in the stack. That is, positions 0, ..., sp-1
358 /* record of basic blocks already seen by depth-first search */
359 sbitmap visited_blocks;
361 typedef struct depth_first_search_dsS *depth_first_search_ds;
363 /* Have print_rtl_and_abort give the same information that fancy_abort
365 #define print_rtl_and_abort() \
366 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
368 /* Forward declarations */
369 static bool try_crossjump_to_edge PARAMS ((int, edge, edge));
370 static bool try_crossjump_bb PARAMS ((int, basic_block));
371 static bool outgoing_edges_match PARAMS ((basic_block, basic_block));
372 static int flow_find_cross_jump PARAMS ((int, basic_block, basic_block,
374 static int count_basic_blocks PARAMS ((rtx));
375 static void find_basic_blocks_1 PARAMS ((rtx));
376 static rtx find_label_refs PARAMS ((rtx, rtx));
377 static void make_edges PARAMS ((rtx, int, int));
378 static void make_label_edge PARAMS ((sbitmap *, basic_block,
380 static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
382 static void commit_one_edge_insertion PARAMS ((edge));
384 static void delete_unreachable_blocks PARAMS ((void));
385 static int can_delete_note_p PARAMS ((rtx));
386 static void expunge_block PARAMS ((basic_block));
387 static int can_delete_label_p PARAMS ((rtx));
388 static int tail_recursion_label_p PARAMS ((rtx));
389 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
391 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
393 static int merge_blocks PARAMS ((edge,basic_block,basic_block,
395 static bool try_optimize_cfg PARAMS ((int));
396 static bool can_fallthru PARAMS ((basic_block, basic_block));
397 static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block));
398 static bool try_simplify_condjump PARAMS ((basic_block));
399 static bool try_forward_edges PARAMS ((basic_block));
400 static void tidy_fallthru_edges PARAMS ((void));
401 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
402 static void verify_wide_reg PARAMS ((int, rtx, rtx));
403 static void verify_local_live_at_start PARAMS ((regset, basic_block));
404 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
405 static void notice_stack_pointer_modification PARAMS ((rtx));
406 static void mark_reg PARAMS ((rtx, void *));
407 static void mark_regs_live_at_end PARAMS ((regset));
408 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
409 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
410 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
411 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
412 static int insn_dead_p PARAMS ((struct propagate_block_info *,
414 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
416 static void mark_set_regs PARAMS ((struct propagate_block_info *,
418 static void mark_set_1 PARAMS ((struct propagate_block_info *,
419 enum rtx_code, rtx, rtx,
421 #ifdef HAVE_conditional_execution
422 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
424 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
425 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
426 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
428 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
429 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
430 static rtx not_reg_cond PARAMS ((rtx));
431 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
434 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
435 rtx, rtx, rtx, rtx, rtx));
436 static void find_auto_inc PARAMS ((struct propagate_block_info *,
438 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
440 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
442 static void mark_used_reg PARAMS ((struct propagate_block_info *,
444 static void mark_used_regs PARAMS ((struct propagate_block_info *,
446 void dump_flow_info PARAMS ((FILE *));
447 void debug_flow_info PARAMS ((void));
448 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
452 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
454 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
456 static void remove_fake_successors PARAMS ((basic_block));
457 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
459 static void flow_edge_list_print PARAMS ((const char *, const edge *,
461 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
463 static int flow_loop_nested_p PARAMS ((struct loop *,
465 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
467 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
468 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
469 static void flow_dfs_compute_reverse_init
470 PARAMS ((depth_first_search_ds));
471 static void flow_dfs_compute_reverse_add_bb
472 PARAMS ((depth_first_search_ds, basic_block));
473 static basic_block flow_dfs_compute_reverse_execute
474 PARAMS ((depth_first_search_ds));
475 static void flow_dfs_compute_reverse_finish
476 PARAMS ((depth_first_search_ds));
477 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
478 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
480 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
481 static void flow_loops_tree_build PARAMS ((struct loops *));
482 static int flow_loop_level_compute PARAMS ((struct loop *, int));
483 static int flow_loops_level_compute PARAMS ((struct loops *));
485 /* Find basic blocks of the current function.
486 F is the first insn of the function and NREGS the number of register
490 find_basic_blocks (f, nregs, file)
492 int nregs ATTRIBUTE_UNUSED;
493 FILE *file ATTRIBUTE_UNUSED;
496 timevar_push (TV_CFG);
498 /* Flush out existing data. */
499 if (basic_block_info != NULL)
505 /* Clear bb->aux on all extant basic blocks. We'll use this as a
506 tag for reuse during create_basic_block, just in case some pass
507 copies around basic block notes improperly. */
508 for (i = 0; i < n_basic_blocks; ++i)
509 BASIC_BLOCK (i)->aux = NULL;
511 VARRAY_FREE (basic_block_info);
514 n_basic_blocks = count_basic_blocks (f);
516 /* Size the basic block table. The actual structures will be allocated
517 by find_basic_blocks_1, since we want to keep the structure pointers
518 stable across calls to find_basic_blocks. */
519 /* ??? This whole issue would be much simpler if we called find_basic_blocks
520 exactly once, and thereafter we don't have a single long chain of
521 instructions at all until close to the end of compilation when we
522 actually lay them out. */
524 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
526 find_basic_blocks_1 (f);
528 /* Record the block to which an insn belongs. */
529 /* ??? This should be done another way, by which (perhaps) a label is
530 tagged directly with the basic block that it starts. It is used for
531 more than that currently, but IMO that is the only valid use. */
533 max_uid = get_max_uid ();
535 /* Leave space for insns life_analysis makes in some cases for auto-inc.
536 These cases are rare, so we don't need too much space. */
537 max_uid += max_uid / 10;
540 compute_bb_for_insn (max_uid);
542 /* Discover the edges of our cfg. */
543 make_edges (label_value_list, 0, n_basic_blocks - 1);
545 /* Do very simple cleanup now, for the benefit of code that runs between
546 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
547 tidy_fallthru_edges ();
549 mark_critical_edges ();
551 #ifdef ENABLE_CHECKING
554 timevar_pop (TV_CFG);
558 check_function_return_warnings ()
560 if (warn_missing_noreturn
561 && !TREE_THIS_VOLATILE (cfun->decl)
562 && EXIT_BLOCK_PTR->pred == NULL
563 && (lang_missing_noreturn_ok_p
564 && !lang_missing_noreturn_ok_p (cfun->decl)))
565 warning ("function might be possible candidate for attribute `noreturn'");
567 /* If we have a path to EXIT, then we do return. */
568 if (TREE_THIS_VOLATILE (cfun->decl)
569 && EXIT_BLOCK_PTR->pred != NULL)
570 warning ("`noreturn' function does return");
572 /* If the clobber_return_insn appears in some basic block, then we
573 do reach the end without returning a value. */
574 else if (warn_return_type
575 && cfun->x_clobber_return_insn != NULL
576 && EXIT_BLOCK_PTR->pred != NULL)
578 int max_uid = get_max_uid ();
580 /* If clobber_return_insn was excised by jump1, then renumber_insns
581 can make max_uid smaller than the number still recorded in our rtx.
582 That's fine, since this is a quick way of verifying that the insn
583 is no longer in the chain. */
584 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
586 /* Recompute insn->block mapping, since the initial mapping is
587 set before we delete unreachable blocks. */
588 compute_bb_for_insn (max_uid);
590 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
591 warning ("control reaches end of non-void function");
596 /* Count the basic blocks of the function. */
599 count_basic_blocks (f)
603 register RTX_CODE prev_code;
604 register int count = 0;
605 int saw_abnormal_edge = 0;
607 prev_code = JUMP_INSN;
608 for (insn = f; insn; insn = NEXT_INSN (insn))
610 enum rtx_code code = GET_CODE (insn);
612 if (code == CODE_LABEL
613 || (GET_RTX_CLASS (code) == 'i'
614 && (prev_code == JUMP_INSN
615 || prev_code == BARRIER
616 || saw_abnormal_edge)))
618 saw_abnormal_edge = 0;
622 /* Record whether this insn created an edge. */
623 if (code == CALL_INSN)
627 /* If there is a nonlocal goto label and the specified
628 region number isn't -1, we have an edge. */
629 if (nonlocal_goto_handler_labels
630 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
631 || INTVAL (XEXP (note, 0)) >= 0))
632 saw_abnormal_edge = 1;
634 else if (can_throw_internal (insn))
635 saw_abnormal_edge = 1;
637 else if (flag_non_call_exceptions
639 && can_throw_internal (insn))
640 saw_abnormal_edge = 1;
646 /* The rest of the compiler works a bit smoother when we don't have to
647 check for the edge case of do-nothing functions with no basic blocks. */
650 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
657 /* Scan a list of insns for labels referred to other than by jumps.
658 This is used to scan the alternatives of a call placeholder. */
660 find_label_refs (f, lvl)
666 for (insn = f; insn; insn = NEXT_INSN (insn))
667 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
671 /* Make a list of all labels referred to other than by jumps
672 (which just don't have the REG_LABEL notes).
674 Make a special exception for labels followed by an ADDR*VEC,
675 as this would be a part of the tablejump setup code.
677 Make a special exception to registers loaded with label
678 values just before jump insns that use them. */
680 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
681 if (REG_NOTE_KIND (note) == REG_LABEL)
683 rtx lab = XEXP (note, 0), next;
685 if ((next = next_nonnote_insn (lab)) != NULL
686 && GET_CODE (next) == JUMP_INSN
687 && (GET_CODE (PATTERN (next)) == ADDR_VEC
688 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
690 else if (GET_CODE (lab) == NOTE)
692 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
693 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
696 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
703 /* Assume that someone emitted code with control flow instructions to the
704 basic block. Update the data structure. */
706 find_sub_basic_blocks (bb)
711 rtx jump_insn = NULL_RTX;
715 basic_block first_bb = bb;
720 if (GET_CODE (insn) == CODE_LABEL)
721 insn = NEXT_INSN (insn);
723 /* Scan insn chain and try to find new basic block boundaries. */
726 enum rtx_code code = GET_CODE (insn);
734 /* On code label, split current basic block. */
736 falltru = split_block (bb, PREV_INSN (insn));
740 remove_edge (falltru);
744 if (LABEL_ALTERNATE_NAME (insn))
745 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
749 /* In case we've previously split insn on the JUMP_INSN, move the
750 block header to proper place. */
753 falltru = split_block (bb, PREV_INSN (insn));
756 remove_edge (falltru);
759 /* We need some special care for those expressions. */
760 if (GET_CODE (insn) == JUMP_INSN)
762 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
763 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
773 insn = NEXT_INSN (insn);
776 /* In case we've got barrier at the end of new insn stream, put it
777 outside basic block. */
778 if (GET_CODE (bb->end) == BARRIER)
779 bb->end = PREV_INSN (bb->end);
781 /* We've possibly replaced the conditional jump by conditional jump
782 followed by cleanup at fallthru edge, so the outgoing edges may
784 purge_dead_edges (bb);
786 /* Now re-scan and wire in all edges. This expect simple (conditional)
787 jumps at the end of each new basic blocks. */
788 make_edges (NULL, first_bb->index, bb->index - 1);
791 /* Find all basic blocks of the function whose first insn is F.
793 Collect and return a list of labels whose addresses are taken. This
794 will be used in make_edges for use with computed gotos. */
797 find_basic_blocks_1 (f)
800 register rtx insn, next;
802 rtx bb_note = NULL_RTX;
808 /* We process the instructions in a slightly different way than we did
809 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
810 closed out the previous block, so that it gets attached at the proper
811 place. Since this form should be equivalent to the previous,
812 count_basic_blocks continues to use the old form as a check. */
814 for (insn = f; insn; insn = next)
816 enum rtx_code code = GET_CODE (insn);
818 next = NEXT_INSN (insn);
824 int kind = NOTE_LINE_NUMBER (insn);
826 /* Look for basic block notes with which to keep the
827 basic_block_info pointers stable. Unthread the note now;
828 we'll put it back at the right place in create_basic_block.
829 Or not at all if we've already found a note in this block. */
830 if (kind == NOTE_INSN_BASIC_BLOCK)
832 if (bb_note == NULL_RTX)
835 next = flow_delete_insn (insn);
841 /* A basic block starts at a label. If we've closed one off due
842 to a barrier or some such, no need to do it again. */
843 if (head != NULL_RTX)
845 create_basic_block (i++, head, end, bb_note);
853 /* A basic block ends at a jump. */
854 if (head == NULL_RTX)
858 /* ??? Make a special check for table jumps. The way this
859 happens is truly and amazingly gross. We are about to
860 create a basic block that contains just a code label and
861 an addr*vec jump insn. Worse, an addr_diff_vec creates
862 its own natural loop.
864 Prevent this bit of brain damage, pasting things together
865 correctly in make_edges.
867 The correct solution involves emitting the table directly
868 on the tablejump instruction as a note, or JUMP_LABEL. */
870 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
871 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
879 goto new_bb_inclusive;
882 /* A basic block ends at a barrier. It may be that an unconditional
883 jump already closed the basic block -- no need to do it again. */
884 if (head == NULL_RTX)
886 goto new_bb_exclusive;
890 /* Record whether this call created an edge. */
891 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
892 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
894 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
896 /* Scan each of the alternatives for label refs. */
897 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
898 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
899 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
900 /* Record its tail recursion label, if any. */
901 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
902 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
905 /* A basic block ends at a call that can either throw or
906 do a non-local goto. */
907 if ((nonlocal_goto_handler_labels && region >= 0)
908 || can_throw_internal (insn))
911 if (head == NULL_RTX)
916 create_basic_block (i++, head, end, bb_note);
917 head = end = NULL_RTX;
925 /* Non-call exceptions generate new blocks just like calls. */
926 if (flag_non_call_exceptions && can_throw_internal (insn))
927 goto new_bb_inclusive;
929 if (head == NULL_RTX)
938 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
942 /* Make a list of all labels referred to other than by jumps.
944 Make a special exception for labels followed by an ADDR*VEC,
945 as this would be a part of the tablejump setup code.
947 Make a special exception to registers loaded with label
948 values just before jump insns that use them. */
950 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
951 if (REG_NOTE_KIND (note) == REG_LABEL)
953 rtx lab = XEXP (note, 0), next;
955 if ((next = next_nonnote_insn (lab)) != NULL
956 && GET_CODE (next) == JUMP_INSN
957 && (GET_CODE (PATTERN (next)) == ADDR_VEC
958 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
960 else if (GET_CODE (lab) == NOTE)
962 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
963 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
966 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
971 if (head != NULL_RTX)
972 create_basic_block (i++, head, end, bb_note);
974 flow_delete_insn (bb_note);
976 if (i != n_basic_blocks)
979 label_value_list = lvl;
980 tail_recursion_label_list = trll;
983 /* Tidy the CFG by deleting unreachable code and whatnot. */
989 timevar_push (TV_CLEANUP_CFG);
990 delete_unreachable_blocks ();
991 if (try_optimize_cfg (mode))
992 delete_unreachable_blocks ();
993 mark_critical_edges ();
995 /* Kill the data we won't maintain. */
996 free_EXPR_LIST_list (&label_value_list);
997 free_EXPR_LIST_list (&tail_recursion_label_list);
998 timevar_pop (TV_CLEANUP_CFG);
1001 /* Create a new basic block consisting of the instructions between
1002 HEAD and END inclusive. Reuses the note and basic block struct
1003 in BB_NOTE, if any. */
1006 create_basic_block (index, head, end, bb_note)
1008 rtx head, end, bb_note;
1013 && ! RTX_INTEGRATED_P (bb_note)
1014 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1017 /* If we found an existing note, thread it back onto the chain. */
1021 if (GET_CODE (head) == CODE_LABEL)
1025 after = PREV_INSN (head);
1029 if (after != bb_note && NEXT_INSN (after) != bb_note)
1030 reorder_insns (bb_note, bb_note, after);
1034 /* Otherwise we must create a note and a basic block structure.
1035 Since we allow basic block structs in rtl, give the struct
1036 the same lifetime by allocating it off the function obstack
1037 rather than using malloc. */
1039 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1040 memset (bb, 0, sizeof (*bb));
1042 if (GET_CODE (head) == CODE_LABEL)
1043 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1046 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1049 NOTE_BASIC_BLOCK (bb_note) = bb;
1052 /* Always include the bb note in the block. */
1053 if (NEXT_INSN (end) == bb_note)
1059 BASIC_BLOCK (index) = bb;
1061 /* Tag the block so that we know it has been used when considering
1062 other basic block notes. */
1066 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
1067 note associated with the BLOCK. */
1070 first_insn_after_basic_block_note (block)
1075 /* Get the first instruction in the block. */
1078 if (insn == NULL_RTX)
1080 if (GET_CODE (insn) == CODE_LABEL)
1081 insn = NEXT_INSN (insn);
1082 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
1085 return NEXT_INSN (insn);
1088 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1089 indexed by INSN_UID. MAX is the size of the array. */
1092 compute_bb_for_insn (max)
1097 if (basic_block_for_insn)
1098 VARRAY_FREE (basic_block_for_insn);
1099 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1101 for (i = 0; i < n_basic_blocks; ++i)
1103 basic_block bb = BASIC_BLOCK (i);
1110 int uid = INSN_UID (insn);
1112 VARRAY_BB (basic_block_for_insn, uid) = bb;
1115 insn = NEXT_INSN (insn);
1120 /* Free the memory associated with the edge structures. */
1128 for (i = 0; i < n_basic_blocks; ++i)
1130 basic_block bb = BASIC_BLOCK (i);
1132 for (e = bb->succ; e; e = n)
1142 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1148 ENTRY_BLOCK_PTR->succ = 0;
1149 EXIT_BLOCK_PTR->pred = 0;
1154 /* Identify the edges between basic blocks MIN to MAX.
1156 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1157 that are otherwise unreachable may be reachable with a non-local goto.
1159 BB_EH_END is an array indexed by basic block number in which we record
1160 the list of exception regions active at the end of the basic block. */
1163 make_edges (label_value_list, min, max)
1164 rtx label_value_list;
1168 sbitmap *edge_cache = NULL;
1170 /* Assume no computed jump; revise as we create edges. */
1171 current_function_has_computed_jump = 0;
1173 /* Heavy use of computed goto in machine-generated code can lead to
1174 nearly fully-connected CFGs. In that case we spend a significant
1175 amount of time searching the edge lists for duplicates. */
1176 if (forced_labels || label_value_list)
1178 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1179 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1182 /* By nature of the way these get numbered, block 0 is always the entry. */
1183 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1185 for (i = min; i <= max; ++i)
1187 basic_block bb = BASIC_BLOCK (i);
1190 int force_fallthru = 0;
1192 if (GET_CODE (bb->head) == CODE_LABEL
1193 && LABEL_ALTERNATE_NAME (bb->head))
1194 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1196 /* Examine the last instruction of the block, and discover the
1197 ways we can leave the block. */
1200 code = GET_CODE (insn);
1203 if (code == JUMP_INSN)
1207 /* Recognize exception handling placeholders. */
1208 if (GET_CODE (PATTERN (insn)) == RESX)
1209 make_eh_edge (edge_cache, bb, insn);
1211 /* Recognize a non-local goto as a branch outside the
1212 current function. */
1213 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1216 /* ??? Recognize a tablejump and do the right thing. */
1217 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1218 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1219 && GET_CODE (tmp) == JUMP_INSN
1220 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1221 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1226 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1227 vec = XVEC (PATTERN (tmp), 0);
1229 vec = XVEC (PATTERN (tmp), 1);
1231 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1232 make_label_edge (edge_cache, bb,
1233 XEXP (RTVEC_ELT (vec, j), 0), 0);
1235 /* Some targets (eg, ARM) emit a conditional jump that also
1236 contains the out-of-range target. Scan for these and
1237 add an edge if necessary. */
1238 if ((tmp = single_set (insn)) != NULL
1239 && SET_DEST (tmp) == pc_rtx
1240 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1241 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1242 make_label_edge (edge_cache, bb,
1243 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1245 #ifdef CASE_DROPS_THROUGH
1246 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1247 us naturally detecting fallthru into the next block. */
1252 /* If this is a computed jump, then mark it as reaching
1253 everything on the label_value_list and forced_labels list. */
1254 else if (computed_jump_p (insn))
1256 current_function_has_computed_jump = 1;
1258 for (x = label_value_list; x; x = XEXP (x, 1))
1259 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1261 for (x = forced_labels; x; x = XEXP (x, 1))
1262 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1265 /* Returns create an exit out. */
1266 else if (returnjump_p (insn))
1267 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1269 /* Otherwise, we have a plain conditional or unconditional jump. */
1272 if (! JUMP_LABEL (insn))
1274 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1278 /* If this is a sibling call insn, then this is in effect a
1279 combined call and return, and so we need an edge to the
1280 exit block. No need to worry about EH edges, since we
1281 wouldn't have created the sibling call in the first place. */
1283 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1284 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1285 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1287 /* If this is a CALL_INSN, then mark it as reaching the active EH
1288 handler for this CALL_INSN. If we're handling non-call
1289 exceptions then any insn can reach any of the active handlers.
1291 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1293 else if (code == CALL_INSN || flag_non_call_exceptions)
1295 /* Add any appropriate EH edges. */
1296 make_eh_edge (edge_cache, bb, insn);
1298 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1300 /* ??? This could be made smarter: in some cases it's possible
1301 to tell that certain calls will not do a nonlocal goto.
1303 For example, if the nested functions that do the nonlocal
1304 gotos do not have their addresses taken, then only calls to
1305 those functions or to other nested functions that use them
1306 could possibly do nonlocal gotos. */
1307 /* We do know that a REG_EH_REGION note with a value less
1308 than 0 is guaranteed not to perform a non-local goto. */
1309 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1310 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1311 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1312 make_label_edge (edge_cache, bb, XEXP (x, 0),
1313 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1317 /* Find out if we can drop through to the next block. */
1318 insn = next_nonnote_insn (insn);
1319 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1320 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1321 else if (i + 1 < n_basic_blocks)
1323 rtx tmp = BLOCK_HEAD (i + 1);
1324 if (GET_CODE (tmp) == NOTE)
1325 tmp = next_nonnote_insn (tmp);
1326 if (force_fallthru || insn == tmp)
1327 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1332 sbitmap_vector_free (edge_cache);
1335 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1336 about the edge that is accumulated between calls. */
1339 make_edge (edge_cache, src, dst, flags)
1340 sbitmap *edge_cache;
1341 basic_block src, dst;
1347 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1348 many edges to them, and we didn't allocate memory for it. */
1349 use_edge_cache = (edge_cache
1350 && src != ENTRY_BLOCK_PTR
1351 && dst != EXIT_BLOCK_PTR);
1353 /* Make sure we don't add duplicate edges. */
1354 switch (use_edge_cache)
1357 /* Quick test for non-existance of the edge. */
1358 if (! TEST_BIT (edge_cache[src->index], dst->index))
1361 /* The edge exists; early exit if no work to do. */
1367 for (e = src->succ; e; e = e->succ_next)
1376 e = (edge) xcalloc (1, sizeof (*e));
1379 e->succ_next = src->succ;
1380 e->pred_next = dst->pred;
1389 SET_BIT (edge_cache[src->index], dst->index);
1392 /* Create an edge from a basic block to a label. */
1395 make_label_edge (edge_cache, src, label, flags)
1396 sbitmap *edge_cache;
1401 if (GET_CODE (label) != CODE_LABEL)
1404 /* If the label was never emitted, this insn is junk, but avoid a
1405 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1406 as a result of a syntax error and a diagnostic has already been
1409 if (INSN_UID (label) == 0)
1412 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1415 /* Create the edges generated by INSN in REGION. */
1418 make_eh_edge (edge_cache, src, insn)
1419 sbitmap *edge_cache;
1423 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1426 handlers = reachable_handlers (insn);
1428 for (i = handlers; i; i = XEXP (i, 1))
1429 make_label_edge (edge_cache, src, XEXP (i, 0),
1430 EDGE_ABNORMAL | EDGE_EH | is_call);
1432 free_INSN_LIST_list (&handlers);
1435 /* Identify critical edges and set the bits appropriately. */
1438 mark_critical_edges ()
1440 int i, n = n_basic_blocks;
1443 /* We begin with the entry block. This is not terribly important now,
1444 but could be if a front end (Fortran) implemented alternate entry
1446 bb = ENTRY_BLOCK_PTR;
1453 /* (1) Critical edges must have a source with multiple successors. */
1454 if (bb->succ && bb->succ->succ_next)
1456 for (e = bb->succ; e; e = e->succ_next)
1458 /* (2) Critical edges must have a destination with multiple
1459 predecessors. Note that we know there is at least one
1460 predecessor -- the edge we followed to get here. */
1461 if (e->dest->pred->pred_next)
1462 e->flags |= EDGE_CRITICAL;
1464 e->flags &= ~EDGE_CRITICAL;
1469 for (e = bb->succ; e; e = e->succ_next)
1470 e->flags &= ~EDGE_CRITICAL;
1475 bb = BASIC_BLOCK (i);
1479 /* Split a block BB after insn INSN creating a new fallthru edge.
1480 Return the new edge. Note that to keep other parts of the compiler happy,
1481 this function renumbers all the basic blocks so that the new
1482 one has a number one greater than the block split. */
1485 split_block (bb, insn)
1495 /* There is no point splitting the block after its end. */
1496 if (bb->end == insn)
1499 /* Create the new structures. */
1500 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1501 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1504 memset (new_bb, 0, sizeof (*new_bb));
1506 new_bb->head = NEXT_INSN (insn);
1507 new_bb->end = bb->end;
1510 new_bb->succ = bb->succ;
1511 bb->succ = new_edge;
1512 new_bb->pred = new_edge;
1513 new_bb->count = bb->count;
1514 new_bb->frequency = bb->frequency;
1515 new_bb->loop_depth = bb->loop_depth;
1518 new_edge->dest = new_bb;
1519 new_edge->flags = EDGE_FALLTHRU;
1520 new_edge->probability = REG_BR_PROB_BASE;
1521 new_edge->count = bb->count;
1523 /* Redirect the src of the successor edges of bb to point to new_bb. */
1524 for (e = new_bb->succ; e; e = e->succ_next)
1527 /* Place the new block just after the block being split. */
1528 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1530 /* Some parts of the compiler expect blocks to be number in
1531 sequential order so insert the new block immediately after the
1532 block being split.. */
1534 for (i = n_basic_blocks - 1; i > j + 1; --i)
1536 basic_block tmp = BASIC_BLOCK (i - 1);
1537 BASIC_BLOCK (i) = tmp;
1541 BASIC_BLOCK (i) = new_bb;
1544 if (GET_CODE (new_bb->head) == CODE_LABEL)
1546 /* Create the basic block note. */
1547 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1549 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1551 /* If the only thing in this new block was the label, make sure
1552 the block note gets included. */
1553 if (new_bb->head == new_bb->end)
1554 new_bb->end = bb_note;
1558 /* Create the basic block note. */
1559 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1561 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1562 new_bb->head = bb_note;
1565 update_bb_for_insn (new_bb);
1567 if (bb->global_live_at_start)
1569 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1570 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1571 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1573 /* We now have to calculate which registers are live at the end
1574 of the split basic block and at the start of the new basic
1575 block. Start with those registers that are known to be live
1576 at the end of the original basic block and get
1577 propagate_block to determine which registers are live. */
1578 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1579 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1580 COPY_REG_SET (bb->global_live_at_end,
1581 new_bb->global_live_at_start);
1587 /* Return label in the head of basic block. Create one if it doesn't exist. */
1592 if (block == EXIT_BLOCK_PTR)
1594 if (GET_CODE (block->head) != CODE_LABEL)
1595 block->head = emit_label_before (gen_label_rtx (), block->head);
1599 /* Return true if the block has no effect and only forwards control flow to
1600 its single destination. */
1602 forwarder_block_p (bb)
1605 rtx insn = bb->head;
1606 if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
1607 || !bb->succ || bb->succ->succ_next)
1610 while (insn != bb->end)
1612 if (active_insn_p (insn))
1614 insn = NEXT_INSN (insn);
1616 return (!active_insn_p (insn)
1617 || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)));
1620 /* Return nonzero if we can reach target from src by falling trought. */
1622 can_fallthru (src, target)
1623 basic_block src, target;
1625 rtx insn = src->end;
1626 rtx insn2 = target->head;
1628 if (src->index + 1 == target->index && !active_insn_p (insn2))
1629 insn2 = next_active_insn (insn2);
1630 /* ??? Later we may add code to move jump tables offline. */
1631 return next_active_insn (insn) == insn2;
1634 /* Attempt to perform edge redirection by replacing possibly complex jump
1635 instruction by unconditional jump or removing jump completely.
1636 This can apply only if all edges now point to the same block.
1638 The parameters and return values are equivalent to redirect_edge_and_branch.
1641 try_redirect_by_replacing_jump (e, target)
1645 basic_block src = e->src;
1646 rtx insn = src->end, kill_from;
1651 /* Verify that all targets will be TARGET. */
1652 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
1653 if (tmp->dest != target && tmp != e)
1655 if (tmp || !onlyjump_p (insn))
1658 /* Avoid removing branch with side effects. */
1659 set = single_set (insn);
1660 if (!set || side_effects_p (set))
1663 /* In case we zap a conditional jump, we'll need to kill
1664 the cc0 setter too. */
1667 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
1668 kill_from = PREV_INSN (insn);
1671 /* See if we can create the fallthru edge. */
1672 if (can_fallthru (src, target))
1674 src->end = PREV_INSN (kill_from);
1676 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
1679 /* Selectivly unlink whole insn chain. */
1680 flow_delete_insn_chain (kill_from, PREV_INSN (target->head));
1682 /* If this already is simplejump, redirect it. */
1683 else if (simplejump_p (insn))
1685 if (e->dest == target)
1688 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
1689 INSN_UID (insn), e->dest->index, target->index);
1690 redirect_jump (insn, block_label (target), 0);
1692 /* Or replace possibly complicated jump insn by simple jump insn. */
1695 rtx target_label = block_label (target);
1698 src->end = emit_jump_insn_before (gen_jump (target_label), kill_from);
1699 JUMP_LABEL (src->end) = target_label;
1700 LABEL_NUSES (target_label)++;
1701 if (basic_block_for_insn)
1702 set_block_for_new_insns (src->end, src);
1704 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
1705 INSN_UID (insn), INSN_UID (src->end));
1707 flow_delete_insn_chain (kill_from, insn);
1709 barrier = next_nonnote_insn (src->end);
1710 if (!barrier || GET_CODE (barrier) != BARRIER)
1711 emit_barrier_after (src->end);
1714 /* Keep only one edge out and set proper flags. */
1715 while (src->succ->succ_next)
1716 remove_edge (src->succ);
1719 e->flags = EDGE_FALLTHRU;
1722 e->probability = REG_BR_PROB_BASE;
1723 e->count = src->count;
1725 /* We don't want a block to end on a line-number note since that has
1726 the potential of changing the code between -g and not -g. */
1727 while (GET_CODE (e->src->end) == NOTE
1728 && NOTE_LINE_NUMBER (e->src->end) >= 0)
1730 rtx prev = PREV_INSN (e->src->end);
1731 flow_delete_insn (e->src->end);
1735 if (e->dest != target)
1736 redirect_edge_succ (e, target);
1740 /* Attempt to change code to redirect edge E to TARGET.
1741 Don't do that on expense of adding new instructions or reordering
1744 Function can be also called with edge destionation equivalent to the
1745 TARGET. Then it should try the simplifications and do nothing if
1748 Return true if transformation suceeded. We still return flase in case
1749 E already destinated TARGET and we didn't managed to simplify instruction
1752 redirect_edge_and_branch (e, target)
1757 rtx old_label = e->dest->head;
1758 basic_block src = e->src;
1759 rtx insn = src->end;
1761 if (e->flags & EDGE_COMPLEX)
1764 if (try_redirect_by_replacing_jump (e, target))
1766 /* Do this fast path late, as we want above code to simplify for cases
1767 where called on single edge leaving basic block containing nontrivial
1769 else if (e->dest == target)
1772 /* We can only redirect non-fallthru edges of jump insn. */
1773 if (e->flags & EDGE_FALLTHRU)
1775 if (GET_CODE (insn) != JUMP_INSN)
1778 /* Recognize a tablejump and adjust all matching cases. */
1779 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1780 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1781 && GET_CODE (tmp) == JUMP_INSN
1782 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1783 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1787 rtx new_label = block_label (target);
1789 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1790 vec = XVEC (PATTERN (tmp), 0);
1792 vec = XVEC (PATTERN (tmp), 1);
1794 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1795 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1797 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
1798 --LABEL_NUSES (old_label);
1799 ++LABEL_NUSES (new_label);
1802 /* Handle casesi dispatch insns */
1803 if ((tmp = single_set (insn)) != NULL
1804 && SET_DEST (tmp) == pc_rtx
1805 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1806 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1807 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1809 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1811 --LABEL_NUSES (old_label);
1812 ++LABEL_NUSES (new_label);
1817 /* ?? We may play the games with moving the named labels from
1818 one basic block to the other in case only one computed_jump is
1820 if (computed_jump_p (insn))
1823 /* A return instruction can't be redirected. */
1824 if (returnjump_p (insn))
1827 /* If the insn doesn't go where we think, we're confused. */
1828 if (JUMP_LABEL (insn) != old_label)
1830 redirect_jump (insn, block_label (target), 0);
1834 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
1835 e->src->index, e->dest->index, target->index);
1836 if (e->dest != target)
1839 /* Check whether the edge is already present. */
1840 for (s = src->succ; s; s=s->succ_next)
1841 if (s->dest == target)
1845 s->flags |= e->flags;
1846 s->probability += e->probability;
1847 s->count += e->count;
1851 redirect_edge_succ (e, target);
1856 /* Redirect edge even at the expense of creating new jump insn or
1857 basic block. Return new basic block if created, NULL otherwise.
1858 Abort if converison is impossible. */
1860 redirect_edge_and_branch_force (e, target)
1870 if (redirect_edge_and_branch (e, target))
1872 if (e->dest == target)
1874 if (e->flags & EDGE_ABNORMAL)
1876 if (!(e->flags & EDGE_FALLTHRU))
1879 e->flags &= ~EDGE_FALLTHRU;
1880 label = block_label (target);
1881 /* Case of the fallthru block. */
1882 if (!e->src->succ->succ_next)
1884 e->src->end = emit_jump_insn_after (gen_jump (label), e->src->end);
1885 JUMP_LABEL (e->src->end) = label;
1886 LABEL_NUSES (label)++;
1887 if (basic_block_for_insn)
1888 set_block_for_new_insns (e->src->end, e->src);
1889 emit_barrier_after (e->src->end);
1891 fprintf (rtl_dump_file,
1892 "Emitting jump insn %i to redirect edge %i->%i to %i\n",
1893 INSN_UID (e->src->end), e->src->index, e->dest->index,
1895 redirect_edge_succ (e, target);
1898 /* Redirecting fallthru edge of the conditional needs extra work. */
1901 fprintf (rtl_dump_file,
1902 "Emitting jump insn %i in new BB to redirect edge %i->%i to %i\n",
1903 INSN_UID (e->src->end), e->src->index, e->dest->index,
1906 /* Create the new structures. */
1907 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1908 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1911 memset (new_bb, 0, sizeof (*new_bb));
1913 new_bb->end = new_bb->head = e->src->end;
1914 new_bb->succ = NULL;
1915 new_bb->pred = new_edge;
1916 new_bb->count = e->count;
1917 new_bb->frequency = e->probability * e->src->frequency / REG_BR_PROB_BASE;
1918 new_bb->loop_depth = e->dest->loop_depth;
1920 new_edge->flags = EDGE_FALLTHRU;
1921 new_edge->probability = e->probability;
1922 new_edge->count = e->count;
1924 if (e->dest->global_live_at_start)
1926 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1927 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1928 COPY_REG_SET (new_bb->global_live_at_start,
1929 target->global_live_at_start);
1930 COPY_REG_SET (new_bb->global_live_at_end, new_bb->global_live_at_start);
1934 new_edge->src = e->src;
1935 new_edge->dest = new_bb;
1936 new_edge->succ_next = e->src->succ;
1937 e->src->succ = new_edge;
1938 new_edge->pred_next = NULL;
1940 /* Redirect old edge. */
1941 redirect_edge_succ (e, target);
1942 redirect_edge_pred (e, new_bb);
1943 e->probability = REG_BR_PROB_BASE;
1945 /* Place the new block just after the block being split. */
1946 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1948 /* Some parts of the compiler expect blocks to be number in
1949 sequential order so insert the new block immediately after the
1950 block being split.. */
1951 j = new_edge->src->index;
1952 for (i = n_basic_blocks - 1; i > j + 1; --i)
1954 basic_block tmp = BASIC_BLOCK (i - 1);
1955 BASIC_BLOCK (i) = tmp;
1959 BASIC_BLOCK (i) = new_bb;
1962 /* Create the basic block note. */
1963 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, new_bb->head);
1964 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1965 new_bb->head = bb_note;
1967 new_bb->end = emit_jump_insn_after (gen_jump (label), new_bb->head);
1968 JUMP_LABEL (new_bb->end) = label;
1969 LABEL_NUSES (label)++;
1970 if (basic_block_for_insn)
1971 set_block_for_new_insns (new_bb->end, new_bb);
1972 emit_barrier_after (new_bb->end);
1976 /* Split a (typically critical) edge. Return the new block.
1977 Abort on abnormal edges.
1979 ??? The code generally expects to be called on critical edges.
1980 The case of a block ending in an unconditional jump to a
1981 block with multiple predecessors is not handled optimally. */
1984 split_edge (edge_in)
1987 basic_block old_pred, bb, old_succ;
1992 /* Abnormal edges cannot be split. */
1993 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1996 old_pred = edge_in->src;
1997 old_succ = edge_in->dest;
1999 /* Create the new structures. */
2000 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
2001 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
2004 memset (bb, 0, sizeof (*bb));
2006 /* ??? This info is likely going to be out of date very soon. */
2007 if (old_succ->global_live_at_start)
2009 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2010 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2011 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
2012 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
2016 bb->succ = edge_out;
2017 bb->count = edge_in->count;
2018 bb->frequency = (edge_in->probability * edge_in->src->frequency
2019 / REG_BR_PROB_BASE);
2021 edge_in->flags &= ~EDGE_CRITICAL;
2023 edge_out->pred_next = old_succ->pred;
2024 edge_out->succ_next = NULL;
2026 edge_out->dest = old_succ;
2027 edge_out->flags = EDGE_FALLTHRU;
2028 edge_out->probability = REG_BR_PROB_BASE;
2029 edge_out->count = edge_in->count;
2031 old_succ->pred = edge_out;
2033 /* Tricky case -- if there existed a fallthru into the successor
2034 (and we're not it) we must add a new unconditional jump around
2035 the new block we're actually interested in.
2037 Further, if that edge is critical, this means a second new basic
2038 block must be created to hold it. In order to simplify correct
2039 insn placement, do this before we touch the existing basic block
2040 ordering for the block we were really wanting. */
2041 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2044 for (e = edge_out->pred_next; e; e = e->pred_next)
2045 if (e->flags & EDGE_FALLTHRU)
2050 basic_block jump_block;
2053 if ((e->flags & EDGE_CRITICAL) == 0
2054 && e->src != ENTRY_BLOCK_PTR)
2056 /* Non critical -- we can simply add a jump to the end
2057 of the existing predecessor. */
2058 jump_block = e->src;
2062 /* We need a new block to hold the jump. The simplest
2063 way to do the bulk of the work here is to recursively
2065 jump_block = split_edge (e);
2066 e = jump_block->succ;
2069 /* Now add the jump insn ... */
2070 pos = emit_jump_insn_after (gen_jump (old_succ->head),
2072 jump_block->end = pos;
2073 if (basic_block_for_insn)
2074 set_block_for_new_insns (pos, jump_block);
2075 emit_barrier_after (pos);
2077 /* ... let jump know that label is in use, ... */
2078 JUMP_LABEL (pos) = old_succ->head;
2079 ++LABEL_NUSES (old_succ->head);
2081 /* ... and clear fallthru on the outgoing edge. */
2082 e->flags &= ~EDGE_FALLTHRU;
2084 /* Continue splitting the interesting edge. */
2088 /* Place the new block just in front of the successor. */
2089 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2090 if (old_succ == EXIT_BLOCK_PTR)
2091 j = n_basic_blocks - 1;
2093 j = old_succ->index;
2094 for (i = n_basic_blocks - 1; i > j; --i)
2096 basic_block tmp = BASIC_BLOCK (i - 1);
2097 BASIC_BLOCK (i) = tmp;
2100 BASIC_BLOCK (i) = bb;
2103 /* Create the basic block note.
2105 Where we place the note can have a noticable impact on the generated
2106 code. Consider this cfg:
2116 If we need to insert an insn on the edge from block 0 to block 1,
2117 we want to ensure the instructions we insert are outside of any
2118 loop notes that physically sit between block 0 and block 1. Otherwise
2119 we confuse the loop optimizer into thinking the loop is a phony. */
2120 if (old_succ != EXIT_BLOCK_PTR
2121 && PREV_INSN (old_succ->head)
2122 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
2123 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
2124 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
2125 PREV_INSN (old_succ->head));
2126 else if (old_succ != EXIT_BLOCK_PTR)
2127 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
2129 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
2130 NOTE_BASIC_BLOCK (bb_note) = bb;
2131 bb->head = bb->end = bb_note;
2133 /* For non-fallthry edges, we must adjust the predecessor's
2134 jump instruction to target our new block. */
2135 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2137 if (!redirect_edge_and_branch (edge_in, bb))
2141 redirect_edge_succ (edge_in, bb);
2146 /* Queue instructions for insertion on an edge between two basic blocks.
2147 The new instructions and basic blocks (if any) will not appear in the
2148 CFG until commit_edge_insertions is called. */
2151 insert_insn_on_edge (pattern, e)
2155 /* We cannot insert instructions on an abnormal critical edge.
2156 It will be easier to find the culprit if we die now. */
2157 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
2158 == (EDGE_ABNORMAL|EDGE_CRITICAL))
2161 if (e->insns == NULL_RTX)
2164 push_to_sequence (e->insns);
2166 emit_insn (pattern);
2168 e->insns = get_insns ();
2172 /* Update the CFG for the instructions queued on edge E. */
2175 commit_one_edge_insertion (e)
2178 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
2181 /* Pull the insns off the edge now since the edge might go away. */
2183 e->insns = NULL_RTX;
2185 /* Figure out where to put these things. If the destination has
2186 one predecessor, insert there. Except for the exit block. */
2187 if (e->dest->pred->pred_next == NULL
2188 && e->dest != EXIT_BLOCK_PTR)
2192 /* Get the location correct wrt a code label, and "nice" wrt
2193 a basic block note, and before everything else. */
2195 if (GET_CODE (tmp) == CODE_LABEL)
2196 tmp = NEXT_INSN (tmp);
2197 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
2198 tmp = NEXT_INSN (tmp);
2199 if (tmp == bb->head)
2202 after = PREV_INSN (tmp);
2205 /* If the source has one successor and the edge is not abnormal,
2206 insert there. Except for the entry block. */
2207 else if ((e->flags & EDGE_ABNORMAL) == 0
2208 && e->src->succ->succ_next == NULL
2209 && e->src != ENTRY_BLOCK_PTR)
2212 /* It is possible to have a non-simple jump here. Consider a target
2213 where some forms of unconditional jumps clobber a register. This
2214 happens on the fr30 for example.
2216 We know this block has a single successor, so we can just emit
2217 the queued insns before the jump. */
2218 if (GET_CODE (bb->end) == JUMP_INSN)
2224 /* We'd better be fallthru, or we've lost track of what's what. */
2225 if ((e->flags & EDGE_FALLTHRU) == 0)
2232 /* Otherwise we must split the edge. */
2235 bb = split_edge (e);
2239 /* Now that we've found the spot, do the insertion. */
2241 /* Set the new block number for these insns, if structure is allocated. */
2242 if (basic_block_for_insn)
2245 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
2246 set_block_for_insn (i, bb);
2251 emit_insns_before (insns, before);
2252 if (before == bb->head)
2255 last = prev_nonnote_insn (before);
2259 last = emit_insns_after (insns, after);
2260 if (after == bb->end)
2264 if (returnjump_p (last))
2266 /* ??? Remove all outgoing edges from BB and add one for EXIT.
2267 This is not currently a problem because this only happens
2268 for the (single) epilogue, which already has a fallthru edge
2272 if (e->dest != EXIT_BLOCK_PTR
2273 || e->succ_next != NULL
2274 || (e->flags & EDGE_FALLTHRU) == 0)
2276 e->flags &= ~EDGE_FALLTHRU;
2278 emit_barrier_after (last);
2282 flow_delete_insn (before);
2284 else if (GET_CODE (last) == JUMP_INSN)
2286 find_sub_basic_blocks (bb);
2289 /* Update the CFG for all queued instructions. */
2292 commit_edge_insertions ()
2297 #ifdef ENABLE_CHECKING
2298 verify_flow_info ();
2302 bb = ENTRY_BLOCK_PTR;
2307 for (e = bb->succ; e; e = next)
2309 next = e->succ_next;
2311 commit_one_edge_insertion (e);
2314 if (++i >= n_basic_blocks)
2316 bb = BASIC_BLOCK (i);
2320 /* Add fake edges to the function exit for any non constant calls in
2321 the bitmap of blocks specified by BLOCKS or to the whole CFG if
2322 BLOCKS is zero. Return the nuber of blocks that were split. */
2325 flow_call_edges_add (blocks)
2329 int blocks_split = 0;
2333 /* Map bb indicies into basic block pointers since split_block
2334 will renumber the basic blocks. */
2336 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2340 for (i = 0; i < n_basic_blocks; i++)
2341 bbs[bb_num++] = BASIC_BLOCK (i);
2345 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2347 bbs[bb_num++] = BASIC_BLOCK (i);
2352 /* Now add fake edges to the function exit for any non constant
2353 calls since there is no way that we can determine if they will
2356 for (i = 0; i < bb_num; i++)
2358 basic_block bb = bbs[i];
2362 for (insn = bb->end; ; insn = prev_insn)
2364 prev_insn = PREV_INSN (insn);
2365 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2369 /* Note that the following may create a new basic block
2370 and renumber the existing basic blocks. */
2371 e = split_block (bb, insn);
2375 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2377 if (insn == bb->head)
2383 verify_flow_info ();
2386 return blocks_split;
2389 /* Find unreachable blocks. An unreachable block will have NULL in
2390 block->aux, a non-NULL value indicates the block is reachable. */
2393 find_unreachable_blocks ()
2397 basic_block *tos, *worklist;
2400 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2402 /* Use basic_block->aux as a marker. Clear them all. */
2404 for (i = 0; i < n; ++i)
2405 BASIC_BLOCK (i)->aux = NULL;
2407 /* Add our starting points to the worklist. Almost always there will
2408 be only one. It isn't inconcievable that we might one day directly
2409 support Fortran alternate entry points. */
2411 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2415 /* Mark the block with a handy non-null value. */
2419 /* Iterate: find everything reachable from what we've already seen. */
2421 while (tos != worklist)
2423 basic_block b = *--tos;
2425 for (e = b->succ; e; e = e->succ_next)
2436 /* Delete all unreachable basic blocks. */
2438 delete_unreachable_blocks ()
2442 find_unreachable_blocks ();
2444 /* Delete all unreachable basic blocks. Count down so that we
2445 don't interfere with the block renumbering that happens in
2446 flow_delete_block. */
2448 for (i = n_basic_blocks - 1; i >= 0; --i)
2450 basic_block b = BASIC_BLOCK (i);
2453 /* This block was found. Tidy up the mark. */
2456 flow_delete_block (b);
2459 tidy_fallthru_edges ();
2462 /* Return true if NOTE is not one of the ones that must be kept paired,
2463 so that we may simply delete them. */
2466 can_delete_note_p (note)
2469 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2470 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2473 /* Unlink a chain of insns between START and FINISH, leaving notes
2474 that must be paired. */
2477 flow_delete_insn_chain (start, finish)
2480 /* Unchain the insns one by one. It would be quicker to delete all
2481 of these with a single unchaining, rather than one at a time, but
2482 we need to keep the NOTE's. */
2488 next = NEXT_INSN (start);
2489 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2491 else if (GET_CODE (start) == CODE_LABEL
2492 && ! can_delete_label_p (start))
2494 const char *name = LABEL_NAME (start);
2495 PUT_CODE (start, NOTE);
2496 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2497 NOTE_SOURCE_FILE (start) = name;
2500 next = flow_delete_insn (start);
2502 if (start == finish)
2508 /* Delete the insns in a (non-live) block. We physically delete every
2509 non-deleted-note insn, and update the flow graph appropriately.
2511 Return nonzero if we deleted an exception handler. */
2513 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2514 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2517 flow_delete_block (b)
2520 int deleted_handler = 0;
2523 /* If the head of this block is a CODE_LABEL, then it might be the
2524 label for an exception handler which can't be reached.
2526 We need to remove the label from the exception_handler_label list
2527 and remove the associated NOTE_INSN_EH_REGION_BEG and
2528 NOTE_INSN_EH_REGION_END notes. */
2532 never_reached_warning (insn);
2534 if (GET_CODE (insn) == CODE_LABEL)
2535 maybe_remove_eh_handler (insn);
2537 /* Include any jump table following the basic block. */
2539 if (GET_CODE (end) == JUMP_INSN
2540 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2541 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2542 && GET_CODE (tmp) == JUMP_INSN
2543 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2544 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2547 /* Include any barrier that may follow the basic block. */
2548 tmp = next_nonnote_insn (end);
2549 if (tmp && GET_CODE (tmp) == BARRIER)
2552 /* Selectively delete the entire chain. */
2553 flow_delete_insn_chain (insn, end);
2555 /* Remove the edges into and out of this block. Note that there may
2556 indeed be edges in, if we are removing an unreachable loop. */
2560 for (e = b->pred; e; e = next)
2562 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2565 next = e->pred_next;
2569 for (e = b->succ; e; e = next)
2571 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2574 next = e->succ_next;
2583 /* Remove the basic block from the array, and compact behind it. */
2586 return deleted_handler;
2589 /* Remove block B from the basic block array and compact behind it. */
2595 int i, n = n_basic_blocks;
2597 for (i = b->index; i + 1 < n; ++i)
2599 basic_block x = BASIC_BLOCK (i + 1);
2600 BASIC_BLOCK (i) = x;
2604 basic_block_info->num_elements--;
2608 /* Delete INSN by patching it out. Return the next insn. */
2611 flow_delete_insn (insn)
2614 rtx prev = PREV_INSN (insn);
2615 rtx next = NEXT_INSN (insn);
2618 PREV_INSN (insn) = NULL_RTX;
2619 NEXT_INSN (insn) = NULL_RTX;
2620 INSN_DELETED_P (insn) = 1;
2623 NEXT_INSN (prev) = next;
2625 PREV_INSN (next) = prev;
2627 set_last_insn (prev);
2629 if (GET_CODE (insn) == CODE_LABEL)
2630 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2632 /* If deleting a jump, decrement the use count of the label. Deleting
2633 the label itself should happen in the normal course of block merging. */
2634 if (GET_CODE (insn) == JUMP_INSN
2635 && JUMP_LABEL (insn)
2636 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2637 LABEL_NUSES (JUMP_LABEL (insn))--;
2639 /* Also if deleting an insn that references a label. */
2640 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2641 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2642 LABEL_NUSES (XEXP (note, 0))--;
2644 if (GET_CODE (insn) == JUMP_INSN
2645 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2646 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2648 rtx pat = PATTERN (insn);
2649 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
2650 int len = XVECLEN (pat, diff_vec_p);
2653 for (i = 0; i < len; i++)
2654 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
2660 /* True if a given label can be deleted. */
2663 can_delete_label_p (label)
2668 if (LABEL_PRESERVE_P (label))
2671 for (x = forced_labels; x; x = XEXP (x, 1))
2672 if (label == XEXP (x, 0))
2674 for (x = label_value_list; x; x = XEXP (x, 1))
2675 if (label == XEXP (x, 0))
2677 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2678 if (label == XEXP (x, 0))
2681 /* User declared labels must be preserved. */
2682 if (LABEL_NAME (label) != 0)
2689 tail_recursion_label_p (label)
2694 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2695 if (label == XEXP (x, 0))
2701 /* Blocks A and B are to be merged into a single block A. The insns
2702 are already contiguous, hence `nomove'. */
2705 merge_blocks_nomove (a, b)
2709 rtx b_head, b_end, a_end;
2710 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2713 /* If there was a CODE_LABEL beginning B, delete it. */
2716 if (GET_CODE (b_head) == CODE_LABEL)
2718 /* Detect basic blocks with nothing but a label. This can happen
2719 in particular at the end of a function. */
2720 if (b_head == b_end)
2722 del_first = del_last = b_head;
2723 b_head = NEXT_INSN (b_head);
2726 /* Delete the basic block note. */
2727 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2729 if (b_head == b_end)
2734 b_head = NEXT_INSN (b_head);
2737 /* If there was a jump out of A, delete it. */
2739 if (GET_CODE (a_end) == JUMP_INSN)
2743 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2744 if (GET_CODE (prev) != NOTE
2745 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2752 /* If this was a conditional jump, we need to also delete
2753 the insn that set cc0. */
2754 if (prev && sets_cc0_p (prev))
2757 prev = prev_nonnote_insn (prev);
2766 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2767 del_first = NEXT_INSN (a_end);
2769 /* Delete everything marked above as well as crap that might be
2770 hanging out between the two blocks. */
2771 flow_delete_insn_chain (del_first, del_last);
2773 /* Normally there should only be one successor of A and that is B, but
2774 partway though the merge of blocks for conditional_execution we'll
2775 be merging a TEST block with THEN and ELSE successors. Free the
2776 whole lot of them and hope the caller knows what they're doing. */
2778 remove_edge (a->succ);
2780 /* Adjust the edges out of B for the new owner. */
2781 for (e = b->succ; e; e = e->succ_next)
2785 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2786 b->pred = b->succ = NULL;
2788 /* Reassociate the insns of B with A. */
2791 if (basic_block_for_insn)
2793 BLOCK_FOR_INSN (b_head) = a;
2794 while (b_head != b_end)
2796 b_head = NEXT_INSN (b_head);
2797 BLOCK_FOR_INSN (b_head) = a;
2807 /* Blocks A and B are to be merged into a single block. A has no incoming
2808 fallthru edge, so it can be moved before B without adding or modifying
2809 any jumps (aside from the jump from A to B). */
2812 merge_blocks_move_predecessor_nojumps (a, b)
2815 rtx start, end, barrier;
2821 barrier = next_nonnote_insn (end);
2822 if (GET_CODE (barrier) != BARRIER)
2824 flow_delete_insn (barrier);
2826 /* Move block and loop notes out of the chain so that we do not
2827 disturb their order.
2829 ??? A better solution would be to squeeze out all the non-nested notes
2830 and adjust the block trees appropriately. Even better would be to have
2831 a tighter connection between block trees and rtl so that this is not
2833 start = squeeze_notes (start, end);
2835 /* Scramble the insn chain. */
2836 if (end != PREV_INSN (b->head))
2837 reorder_insns (start, end, PREV_INSN (b->head));
2841 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2842 a->index, b->index);
2845 /* Swap the records for the two blocks around. Although we are deleting B,
2846 A is now where B was and we want to compact the BB array from where
2848 BASIC_BLOCK (a->index) = b;
2849 BASIC_BLOCK (b->index) = a;
2851 a->index = b->index;
2854 /* Now blocks A and B are contiguous. Merge them. */
2855 merge_blocks_nomove (a, b);
2860 /* Blocks A and B are to be merged into a single block. B has no outgoing
2861 fallthru edge, so it can be moved after A without adding or modifying
2862 any jumps (aside from the jump from A to B). */
2865 merge_blocks_move_successor_nojumps (a, b)
2868 rtx start, end, barrier;
2872 barrier = NEXT_INSN (end);
2874 /* Recognize a jump table following block B. */
2876 && GET_CODE (barrier) == CODE_LABEL
2877 && NEXT_INSN (barrier)
2878 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2879 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2880 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2882 end = NEXT_INSN (barrier);
2883 barrier = NEXT_INSN (end);
2886 /* There had better have been a barrier there. Delete it. */
2887 if (barrier && GET_CODE (barrier) == BARRIER)
2888 flow_delete_insn (barrier);
2890 /* Move block and loop notes out of the chain so that we do not
2891 disturb their order.
2893 ??? A better solution would be to squeeze out all the non-nested notes
2894 and adjust the block trees appropriately. Even better would be to have
2895 a tighter connection between block trees and rtl so that this is not
2897 start = squeeze_notes (start, end);
2899 /* Scramble the insn chain. */
2900 reorder_insns (start, end, a->end);
2902 /* Now blocks A and B are contiguous. Merge them. */
2903 merge_blocks_nomove (a, b);
2907 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2908 b->index, a->index);
2914 /* Attempt to merge basic blocks that are potentially non-adjacent.
2915 Return true iff the attempt succeeded. */
2918 merge_blocks (e, b, c, mode)
2923 /* If C has a tail recursion label, do not merge. There is no
2924 edge recorded from the call_placeholder back to this label, as
2925 that would make optimize_sibling_and_tail_recursive_calls more
2926 complex for no gain. */
2927 if (GET_CODE (c->head) == CODE_LABEL
2928 && tail_recursion_label_p (c->head))
2931 /* If B has a fallthru edge to C, no need to move anything. */
2932 if (e->flags & EDGE_FALLTHRU)
2934 merge_blocks_nomove (b, c);
2938 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2939 b->index, c->index);
2944 /* Otherwise we will need to move code around. Do that only if expensive
2945 transformations are allowed. */
2946 else if (mode & CLEANUP_EXPENSIVE)
2948 edge tmp_edge, c_fallthru_edge;
2949 int c_has_outgoing_fallthru;
2950 int b_has_incoming_fallthru;
2952 /* Avoid overactive code motion, as the forwarder blocks should be
2953 eliminated by edge redirection instead. One exception might have
2954 been if B is a forwarder block and C has no fallthru edge, but
2955 that should be cleaned up by bb-reorder instead. */
2956 if (forwarder_block_p (b) || forwarder_block_p (c))
2959 /* We must make sure to not munge nesting of lexical blocks,
2960 and loop notes. This is done by squeezing out all the notes
2961 and leaving them there to lie. Not ideal, but functional. */
2963 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2964 if (tmp_edge->flags & EDGE_FALLTHRU)
2966 c_has_outgoing_fallthru = (tmp_edge != NULL);
2967 c_fallthru_edge = tmp_edge;
2969 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2970 if (tmp_edge->flags & EDGE_FALLTHRU)
2972 b_has_incoming_fallthru = (tmp_edge != NULL);
2974 /* If B does not have an incoming fallthru, then it can be moved
2975 immediately before C without introducing or modifying jumps.
2976 C cannot be the first block, so we do not have to worry about
2977 accessing a non-existent block. */
2978 if (! b_has_incoming_fallthru)
2979 return merge_blocks_move_predecessor_nojumps (b, c);
2981 /* Otherwise, we're going to try to move C after B. If C does
2982 not have an outgoing fallthru, then it can be moved
2983 immediately after B without introducing or modifying jumps. */
2984 if (! c_has_outgoing_fallthru)
2985 return merge_blocks_move_successor_nojumps (b, c);
2987 /* Otherwise, we'll need to insert an extra jump, and possibly
2988 a new block to contain it. We can't redirect to EXIT_BLOCK_PTR,
2989 as we don't have explicit return instructions before epilogues
2990 are generated, so give up on that case. */
2992 if (c_fallthru_edge->dest != EXIT_BLOCK_PTR
2993 && merge_blocks_move_successor_nojumps (b, c))
2995 basic_block target = c_fallthru_edge->dest;
2999 /* This is a dirty hack to avoid code duplication.
3001 Set edge to point to wrong basic block, so
3002 redirect_edge_and_branch_force will do the trick
3003 and rewire edge back to the original location. */
3004 redirect_edge_succ (c_fallthru_edge, ENTRY_BLOCK_PTR);
3005 new = redirect_edge_and_branch_force (c_fallthru_edge, target);
3007 /* We've just created barrier, but another barrier is
3008 already present in the stream. Avoid the duplicate. */
3009 barrier = next_nonnote_insn (new ? new->end : b->end);
3010 if (GET_CODE (barrier) != BARRIER)
3012 flow_delete_insn (barrier);
3020 /* Simplify a conditional jump around an unconditional jump.
3021 Return true if something changed. */
3024 try_simplify_condjump (cbranch_block)
3025 basic_block cbranch_block;
3027 basic_block jump_block, jump_dest_block, cbranch_dest_block;
3028 edge cbranch_jump_edge, cbranch_fallthru_edge;
3031 /* Verify that there are exactly two successors. */
3032 if (!cbranch_block->succ
3033 || !cbranch_block->succ->succ_next
3034 || cbranch_block->succ->succ_next->succ_next)
3037 /* Verify that we've got a normal conditional branch at the end
3039 cbranch_insn = cbranch_block->end;
3040 if (!any_condjump_p (cbranch_insn))
3043 cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block);
3044 cbranch_jump_edge = BRANCH_EDGE (cbranch_block);
3046 /* The next block must not have multiple predecessors, must not
3047 be the last block in the function, and must contain just the
3048 unconditional jump. */
3049 jump_block = cbranch_fallthru_edge->dest;
3050 if (jump_block->pred->pred_next
3051 || jump_block->index == n_basic_blocks - 1
3052 || !forwarder_block_p (jump_block))
3054 jump_dest_block = jump_block->succ->dest;
3056 /* The conditional branch must target the block after the
3057 unconditional branch. */
3058 cbranch_dest_block = cbranch_jump_edge->dest;
3060 if (!can_fallthru (jump_block, cbranch_dest_block))
3063 /* Invert the conditional branch. Prevent jump.c from deleting
3064 "unreachable" instructions. */
3065 LABEL_NUSES (JUMP_LABEL (cbranch_insn))++;
3066 if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 1))
3068 LABEL_NUSES (JUMP_LABEL (cbranch_insn))--;
3073 fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n",
3074 INSN_UID (cbranch_insn), INSN_UID (jump_block->end));
3076 /* Success. Update the CFG to match. Note that after this point
3077 the edge variable names appear backwards; the redirection is done
3078 this way to preserve edge profile data. */
3079 redirect_edge_succ (cbranch_jump_edge, cbranch_dest_block);
3080 redirect_edge_succ (cbranch_fallthru_edge, jump_dest_block);
3081 cbranch_jump_edge->flags |= EDGE_FALLTHRU;
3082 cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
3084 /* Delete the block with the unconditional jump, and clean up the mess. */
3085 flow_delete_block (jump_block);
3086 tidy_fallthru_edge (cbranch_jump_edge, cbranch_block, cbranch_dest_block);
3091 /* Attempt to forward edges leaving basic block B.
3092 Return true if sucessful. */
3095 try_forward_edges (b)
3098 bool changed = false;
3101 for (e = b->succ; e ; e = next)
3103 basic_block target, first;
3106 next = e->succ_next;
3108 /* Skip complex edges because we don't know how to update them.
3110 Still handle fallthru edges, as we can suceed to forward fallthru
3111 edge to the same place as the branch edge of conditional branch
3112 and turn conditional branch to an unconditonal branch. */
3113 if (e->flags & EDGE_COMPLEX)
3116 target = first = e->dest;
3119 /* Look for the real destination of the jump.
3120 Avoid inifinite loop in the infinite empty loop by counting
3121 up to n_basic_blocks. */
3122 while (forwarder_block_p (target)
3123 && target->succ->dest != EXIT_BLOCK_PTR
3124 && counter < n_basic_blocks)
3126 /* Bypass trivial infinite loops. */
3127 if (target == target->succ->dest)
3128 counter = n_basic_blocks;
3129 target = target->succ->dest, counter++;
3132 if (counter >= n_basic_blocks)
3135 fprintf (rtl_dump_file, "Infinite loop in BB %i.\n",
3138 else if (target == first)
3139 ; /* We didn't do anything. */
3140 else if (redirect_edge_and_branch (e, target))
3142 /* We successfully forwarded the edge. Now update profile
3143 data: for each edge we traversed in the chain, remove
3144 the original edge's execution count. */
3147 first->count -= e->count;
3148 first->succ->count -= e->count;
3149 first->frequency -= ((e->probability * b->frequency
3150 + REG_BR_PROB_BASE / 2)
3151 / REG_BR_PROB_BASE);
3152 first = first->succ->dest;
3154 while (first != target);
3161 fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n",
3162 b->index, e->dest->index, target->index);
3169 /* Look through the insns at the end of BB1 and BB2 and find the longest
3170 sequence that are equivalent. Store the first insns for that sequence
3171 in *F1 and *F2 and return the sequence length.
3173 To simplify callers of this function, if the blocks match exactly,
3174 store the head of the blocks in *F1 and *F2. */
3177 flow_find_cross_jump (mode, bb1, bb2, f1, f2)
3178 int mode ATTRIBUTE_UNUSED;
3179 basic_block bb1, bb2;
3182 rtx i1, i2, p1, p2, last1, last2, afterlast1, afterlast2;
3185 /* Skip simple jumps at the end of the blocks. Complex jumps still
3186 need to be compared for equivalence, which we'll do below. */
3189 if (onlyjump_p (i1))
3190 i1 = PREV_INSN (i1);
3192 if (onlyjump_p (i2))
3193 i2 = PREV_INSN (i2);
3195 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
3199 while ((GET_CODE (i1) == NOTE && i1 != bb1->head))
3200 i1 = PREV_INSN (i1);
3201 while ((GET_CODE (i2) == NOTE && i2 != bb2->head))
3202 i2 = PREV_INSN (i2);
3204 if (i1 == bb1->head || i2 == bb2->head)
3207 /* Verify that I1 and I2 are equivalent. */
3209 if (GET_CODE (i1) != GET_CODE (i2))
3215 /* If this is a CALL_INSN, compare register usage information.
3216 If we don't check this on stack register machines, the two
3217 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3218 numbers of stack registers in the same basic block.
3219 If we don't check this on machines with delay slots, a delay slot may
3220 be filled that clobbers a parameter expected by the subroutine.
3222 ??? We take the simple route for now and assume that if they're
3223 equal, they were constructed identically. */
3225 if (GET_CODE (i1) == CALL_INSN
3226 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3227 CALL_INSN_FUNCTION_USAGE (i2)))
3231 /* If cross_jump_death_matters is not 0, the insn's mode
3232 indicates whether or not the insn contains any stack-like
3235 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
3237 /* If register stack conversion has already been done, then
3238 death notes must also be compared before it is certain that
3239 the two instruction streams match. */
3242 HARD_REG_SET i1_regset, i2_regset;
3244 CLEAR_HARD_REG_SET (i1_regset);
3245 CLEAR_HARD_REG_SET (i2_regset);
3247 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3248 if (REG_NOTE_KIND (note) == REG_DEAD
3249 && STACK_REG_P (XEXP (note, 0)))
3250 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3252 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3253 if (REG_NOTE_KIND (note) == REG_DEAD
3254 && STACK_REG_P (XEXP (note, 0)))
3255 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3257 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3266 if (GET_CODE (p1) != GET_CODE (p2))
3269 if (! rtx_renumbered_equal_p (p1, p2))
3271 /* The following code helps take care of G++ cleanups. */
3272 rtx equiv1 = find_reg_equal_equiv_note (i1);
3273 rtx equiv2 = find_reg_equal_equiv_note (i2);
3275 if (equiv1 && equiv2
3276 /* If the equivalences are not to a constant, they may
3277 reference pseudos that no longer exist, so we can't
3279 && CONSTANT_P (XEXP (equiv1, 0))
3280 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3282 rtx s1 = single_set (i1);
3283 rtx s2 = single_set (i2);
3284 if (s1 != 0 && s2 != 0
3285 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3287 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3288 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3289 if (! rtx_renumbered_equal_p (p1, p2))
3291 else if (apply_change_group ())
3299 /* Don't begin a cross-jump with a USE or CLOBBER insn. */
3300 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3302 afterlast1 = last1, afterlast2 = last2;
3303 last1 = i1, last2 = i2;
3306 i1 = PREV_INSN (i1);
3307 i2 = PREV_INSN (i2);
3313 /* Don't allow the insn after a compare to be shared by
3314 cross-jumping unless the compare is also shared. */
3315 if (reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1))
3316 last1 = afterlast1, last2 = afterlast2, ninsns--;
3320 /* Include preceeding notes and labels in the cross-jump. One,
3321 this may bring us to the head of the blocks as requested above.
3322 Two, it keeps line number notes as matched as may be. */
3325 while (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == NOTE)
3326 last1 = PREV_INSN (last1);
3327 if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL)
3328 last1 = PREV_INSN (last1);
3329 while (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == NOTE)
3330 last2 = PREV_INSN (last2);
3331 if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL)
3332 last2 = PREV_INSN (last2);
3341 /* Return true iff outgoing edges of BB1 and BB2 match, together with
3342 the branch instruction. This means that if we commonize the control
3343 flow before end of the basic block, the semantic remains unchanged.
3345 We may assume that there exists one edge with a common destination. */
3348 outgoing_edges_match (bb1, bb2)
3352 /* If BB1 has only one successor, we must be looking at an unconditional
3353 jump. Which, by the assumption above, means that we only need to check
3354 that BB2 has one successor. */
3355 if (bb1->succ && !bb1->succ->succ_next)
3356 return (bb2->succ && !bb2->succ->succ_next);
3358 /* Match conditional jumps - this may get tricky when fallthru and branch
3359 edges are crossed. */
3361 && bb1->succ->succ_next
3362 && !bb1->succ->succ_next->succ_next
3363 && any_condjump_p (bb1->end))
3365 edge b1, f1, b2, f2;
3366 bool reverse, match;
3367 rtx set1, set2, cond1, cond2;
3368 enum rtx_code code1, code2;
3371 || !bb2->succ->succ_next
3372 || bb1->succ->succ_next->succ_next
3373 || !any_condjump_p (bb2->end))
3376 b1 = BRANCH_EDGE (bb1);
3377 b2 = BRANCH_EDGE (bb2);
3378 f1 = FALLTHRU_EDGE (bb1);
3379 f2 = FALLTHRU_EDGE (bb2);
3381 /* Get around possible forwarders on fallthru edges. Other cases
3382 should be optimized out already. */
3383 if (forwarder_block_p (f1->dest))
3384 f1 = f1->dest->succ;
3385 if (forwarder_block_p (f2->dest))
3386 f2 = f2->dest->succ;
3388 /* To simplify use of this function, return false if there are
3389 unneeded forwarder blocks. These will get eliminated later
3390 during cleanup_cfg. */
3391 if (forwarder_block_p (f1->dest)
3392 || forwarder_block_p (f2->dest)
3393 || forwarder_block_p (b1->dest)
3394 || forwarder_block_p (b2->dest))
3397 if (f1->dest == f2->dest && b1->dest == b2->dest)
3399 else if (f1->dest == b2->dest && b1->dest == f2->dest)
3404 set1 = pc_set (bb1->end);
3405 set2 = pc_set (bb2->end);
3406 if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
3407 != (XEXP (SET_SRC (set2), 1) == pc_rtx))
3410 cond1 = XEXP (SET_SRC (set1), 0);
3411 cond2 = XEXP (SET_SRC (set2), 0);
3412 code1 = GET_CODE (cond1);
3414 code2 = reversed_comparison_code (cond2, bb2->end);
3416 code2 = GET_CODE (cond2);
3417 if (code2 == UNKNOWN)
3420 /* Verify codes and operands match. */
3421 match = ((code1 == code2
3422 && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
3423 && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
3424 || (code1 == swap_condition (code2)
3425 && rtx_renumbered_equal_p (XEXP (cond1, 1),
3427 && rtx_renumbered_equal_p (XEXP (cond1, 0),
3430 /* If we return true, we will join the blocks. Which means that
3431 we will only have one branch prediction bit to work with. Thus
3432 we require the existing branches to have probabilities that are
3434 /* ??? We should use bb->frequency to allow merging in infrequently
3435 executed blocks, but at the moment it is not available when
3436 cleanup_cfg is run. */
3437 if (match && !optimize_size)
3441 note1 = find_reg_note (bb1->end, REG_BR_PROB, 0);
3442 note2 = find_reg_note (bb2->end, REG_BR_PROB, 0);
3446 prob1 = INTVAL (XEXP (note1, 0));
3447 prob2 = INTVAL (XEXP (note2, 0));
3449 prob2 = REG_BR_PROB_BASE - prob2;
3451 /* Fail if the difference in probabilities is
3453 if (abs (prob1 - prob2) > REG_BR_PROB_BASE / 20)
3456 else if (note1 || note2)
3460 if (rtl_dump_file && match)
3461 fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n",
3462 bb1->index, bb2->index);
3467 /* ??? We can handle computed jumps too. This may be important for
3468 inlined functions containing switch statements. Also jumps w/o
3469 fallthru edges can be handled by simply matching whole insn. */
3473 /* E1 and E2 are edges with the same destination block. Search their
3474 predecessors for common code. If found, redirect control flow from
3475 (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */
3478 try_crossjump_to_edge (mode, e1, e2)
3483 basic_block src1 = e1->src, src2 = e2->src;
3484 basic_block redirect_to;
3485 rtx newpos1, newpos2;
3490 /* Search backward through forwarder blocks. We don't need to worry
3491 about multiple entry or chained forwarders, as they will be optimized
3492 away. We do this to look past the unconditional jump following a
3493 conditional jump that is required due to the current CFG shape. */
3495 && !src1->pred->pred_next
3496 && forwarder_block_p (src1))
3502 && !src2->pred->pred_next
3503 && forwarder_block_p (src2))
3509 /* Nothing to do if we reach ENTRY, or a common source block. */
3510 if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR)
3515 /* Seeing more than 1 forwarder blocks would confuse us later... */
3516 if (forwarder_block_p (e1->dest)
3517 && forwarder_block_p (e1->dest->succ->dest))
3519 if (forwarder_block_p (e2->dest)
3520 && forwarder_block_p (e2->dest->succ->dest))
3523 /* Likewise with dead code (possibly newly created by the other optimizations
3525 if (!src1->pred || !src2->pred)
3528 /* Likewise with complex edges.
3529 ??? We should be able to handle most complex edges later with some
3531 if (e1->flags & EDGE_COMPLEX)
3534 /* Look for the common insn sequence, part the first ... */
3535 if (!outgoing_edges_match (src1, src2))
3538 /* ... and part the second. */
3539 nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2);
3543 /* Avoid splitting if possible. */
3544 if (newpos2 == src2->head)
3549 fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n",
3550 src2->index, nmatch);
3551 redirect_to = split_block (src2, PREV_INSN (newpos2))->dest;
3555 fprintf (rtl_dump_file,
3556 "Cross jumping from bb %i to bb %i; %i common insns\n",
3557 src1->index, src2->index, nmatch);
3559 redirect_to->count += src1->count;
3560 redirect_to->frequency += src1->frequency;
3562 /* Recompute the frequencies and counts of outgoing edges. */
3563 for (s = redirect_to->succ; s; s = s->succ_next)
3566 basic_block d = s->dest;
3568 if (forwarder_block_p (d))
3570 for (s2 = src1->succ; ; s2 = s2->succ_next)
3572 basic_block d2 = s2->dest;
3573 if (forwarder_block_p (d2))
3574 d2 = d2->succ->dest;
3578 s->count += s2->count;
3580 /* Take care to update possible forwarder blocks. We verified
3581 that there is no more than one in the chain, so we can't run
3582 into infinite loop. */
3583 if (forwarder_block_p (s->dest))
3585 s->dest->succ->count += s2->count;
3586 s->dest->count += s2->count;
3587 s->dest->frequency += ((s->probability * s->src->frequency)
3588 / REG_BR_PROB_BASE);
3590 if (forwarder_block_p (s2->dest))
3592 s2->dest->succ->count -= s2->count;
3593 s2->dest->count -= s2->count;
3594 s2->dest->frequency -= ((s->probability * s->src->frequency)
3595 / REG_BR_PROB_BASE);
3597 if (!redirect_to->frequency && !src1->frequency)
3598 s->probability = (s->probability + s2->probability) / 2;
3601 ((s->probability * redirect_to->frequency +
3602 s2->probability * src1->frequency)
3603 / (redirect_to->frequency + src1->frequency));
3606 /* FIXME: enable once probabilities are fetched properly at CFG build. */
3608 note = find_reg_note (redirect_to->end, REG_BR_PROB, 0);
3610 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (redirect_to)->probability);
3613 /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */
3615 /* Skip possible basic block header. */
3616 if (GET_CODE (newpos1) == CODE_LABEL)
3617 newpos1 = NEXT_INSN (newpos1);
3618 if (GET_CODE (newpos1) == NOTE)
3619 newpos1 = NEXT_INSN (newpos1);
3622 /* Emit the jump insn. */
3623 label = block_label (redirect_to);
3624 src1->end = emit_jump_insn_before (gen_jump (label), newpos1);
3625 JUMP_LABEL (src1->end) = label;
3626 LABEL_NUSES (label)++;
3627 if (basic_block_for_insn)
3628 set_block_for_new_insns (src1->end, src1);
3630 /* Delete the now unreachable instructions. */
3631 flow_delete_insn_chain (newpos1, last);
3633 /* Make sure there is a barrier after the new jump. */
3634 last = next_nonnote_insn (src1->end);
3635 if (!last || GET_CODE (last) != BARRIER)
3636 emit_barrier_after (src1->end);
3640 remove_edge (src1->succ);
3641 make_edge (NULL, src1, redirect_to, 0);
3646 /* Search the predecessors of BB for common insn sequences. When found,
3647 share code between them by redirecting control flow. Return true if
3648 any changes made. */
3651 try_crossjump_bb (mode, bb)
3655 edge e, e2, nexte2, nexte, fallthru;
3658 /* Nothing to do if there is not at least two incomming edges. */
3659 if (!bb->pred || !bb->pred->pred_next)
3662 /* It is always cheapest to redirect a block that ends in a branch to
3663 a block that falls through into BB, as that adds no branches to the
3664 program. We'll try that combination first. */
3665 for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next)
3666 if (fallthru->flags & EDGE_FALLTHRU)
3670 for (e = bb->pred; e; e = nexte)
3672 nexte = e->pred_next;
3674 /* Elide complex edges now, as neither try_crossjump_to_edge
3675 nor outgoing_edges_match can handle them. */
3676 if (e->flags & EDGE_COMPLEX)
3679 /* As noted above, first try with the fallthru predecessor. */
3682 /* Don't combine the fallthru edge into anything else.
3683 If there is a match, we'll do it the other way around. */
3687 if (try_crossjump_to_edge (mode, e, fallthru))
3695 /* Non-obvious work limiting check: Recognize that we're going
3696 to call try_crossjump_bb on every basic block. So if we have
3697 two blocks with lots of outgoing edges (a switch) and they
3698 share lots of common destinations, then we would do the
3699 cross-jump check once for each common destination.
3701 Now, if the blocks actually are cross-jump candidates, then
3702 all of their destinations will be shared. Which means that
3703 we only need check them for cross-jump candidacy once. We
3704 can eliminate redundant checks of crossjump(A,B) by arbitrarily
3705 choosing to do the check from the block for which the edge
3706 in question is the first successor of A. */
3707 if (e->src->succ != e)
3710 for (e2 = bb->pred; e2; e2 = nexte2)
3712 nexte2 = e2->pred_next;
3717 /* We've already checked the fallthru edge above. */
3721 /* Again, neither try_crossjump_to_edge nor outgoing_edges_match
3722 can handle complex edges. */
3723 if (e2->flags & EDGE_COMPLEX)
3726 /* The "first successor" check above only prevents multiple
3727 checks of crossjump(A,B). In order to prevent redundant
3728 checks of crossjump(B,A), require that A be the block
3729 with the lowest index. */
3730 if (e->src->index > e2->src->index)
3733 if (try_crossjump_to_edge (mode, e, e2))
3745 /* Do simple CFG optimizations - basic block merging, simplifying of jump
3746 instructions etc. Return nonzero if changes were made. */
3749 try_optimize_cfg (mode)
3753 bool changed_overall = false;
3757 /* Attempt to merge blocks as made possible by edge removal. If a block
3758 has only one successor, and the successor has only one predecessor,
3759 they may be combined. */
3767 fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n",
3770 for (i = 0; i < n_basic_blocks;)
3772 basic_block c, b = BASIC_BLOCK (i);
3774 bool changed_here = false;
3776 /* Delete trivially dead basic blocks. */
3777 while (b->pred == NULL)
3779 c = BASIC_BLOCK (b->index - 1);
3781 fprintf (rtl_dump_file, "Deleting block %i.\n", b->index);
3782 flow_delete_block (b);
3787 /* Remove code labels no longer used. Don't do this before
3788 CALL_PLACEHOLDER is removed, as some branches may be hidden
3790 if (b->pred->pred_next == NULL
3791 && (b->pred->flags & EDGE_FALLTHRU)
3792 && !(b->pred->flags & EDGE_COMPLEX)
3793 && GET_CODE (b->head) == CODE_LABEL
3794 && (!(mode & CLEANUP_PRE_SIBCALL)
3795 || !tail_recursion_label_p (b->head))
3796 /* If previous block ends with condjump jumping to next BB,
3797 we can't delete the label. */
3798 && (b->pred->src == ENTRY_BLOCK_PTR
3799 || !reg_mentioned_p (b->head, b->pred->src->end)))
3801 rtx label = b->head;
3802 b->head = NEXT_INSN (b->head);
3803 flow_delete_insn_chain (label, label);
3805 fprintf (rtl_dump_file, "Deleted label in block %i.\n",
3809 /* If we fall through an empty block, we can remove it. */
3810 if (b->pred->pred_next == NULL
3811 && (b->pred->flags & EDGE_FALLTHRU)
3812 && GET_CODE (b->head) != CODE_LABEL
3813 && forwarder_block_p (b)
3814 /* Note that forwarder_block_p true ensures that there
3815 is a successor for this block. */
3816 && (b->succ->flags & EDGE_FALLTHRU)
3817 && n_basic_blocks > 1)
3820 fprintf (rtl_dump_file, "Deleting fallthru block %i.\n",
3822 c = BASIC_BLOCK (b->index ? b->index - 1 : 1);
3823 redirect_edge_succ (b->pred, b->succ->dest);
3824 flow_delete_block (b);
3829 /* Merge blocks. Loop because chains of blocks might be
3831 while ((s = b->succ) != NULL
3832 && s->succ_next == NULL
3833 && !(s->flags & EDGE_COMPLEX)
3834 && (c = s->dest) != EXIT_BLOCK_PTR
3835 && c->pred->pred_next == NULL
3836 /* If the jump insn has side effects,
3837 we can't kill the edge. */
3838 && (GET_CODE (b->end) != JUMP_INSN
3839 || onlyjump_p (b->end))
3840 && merge_blocks (s, b, c, mode))
3841 changed_here = true;
3843 /* Simplify branch over branch. */
3844 if ((mode & CLEANUP_EXPENSIVE) && try_simplify_condjump (b))
3845 changed_here = true;
3847 /* If B has a single outgoing edge, but uses a non-trivial jump
3848 instruction without side-effects, we can either delete the
3849 jump entirely, or replace it with a simple unconditional jump.
3850 Use redirect_edge_and_branch to do the dirty work. */
3852 && ! b->succ->succ_next
3853 && b->succ->dest != EXIT_BLOCK_PTR
3854 && onlyjump_p (b->end)
3855 && redirect_edge_and_branch (b->succ, b->succ->dest))
3856 changed_here = true;
3858 /* Simplify branch to branch. */
3859 if (try_forward_edges (b))
3860 changed_here = true;
3862 /* Look for shared code between blocks. */
3863 if ((mode & CLEANUP_CROSSJUMP)
3864 && try_crossjump_bb (mode, b))
3865 changed_here = true;
3867 /* Don't get confused by the index shift caused by deleting
3875 if ((mode & CLEANUP_CROSSJUMP)
3876 && try_crossjump_bb (mode, EXIT_BLOCK_PTR))
3879 #ifdef ENABLE_CHECKING
3881 verify_flow_info ();
3884 changed_overall |= changed;
3887 return changed_overall;
3890 /* The given edge should potentially be a fallthru edge. If that is in
3891 fact true, delete the jump and barriers that are in the way. */
3894 tidy_fallthru_edge (e, b, c)
3900 /* ??? In a late-running flow pass, other folks may have deleted basic
3901 blocks by nopping out blocks, leaving multiple BARRIERs between here
3902 and the target label. They ought to be chastized and fixed.
3904 We can also wind up with a sequence of undeletable labels between
3905 one block and the next.
3907 So search through a sequence of barriers, labels, and notes for
3908 the head of block C and assert that we really do fall through. */
3910 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
3913 /* Remove what will soon cease being the jump insn from the source block.
3914 If block B consisted only of this single jump, turn it into a deleted
3917 if (GET_CODE (q) == JUMP_INSN
3919 && (any_uncondjump_p (q)
3920 || (b->succ == e && e->succ_next == NULL)))
3923 /* If this was a conditional jump, we need to also delete
3924 the insn that set cc0. */
3925 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
3932 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
3933 NOTE_SOURCE_FILE (q) = 0;
3939 /* We don't want a block to end on a line-number note since that has
3940 the potential of changing the code between -g and not -g. */
3941 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
3948 /* Selectively unlink the sequence. */
3949 if (q != PREV_INSN (c->head))
3950 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
3952 e->flags |= EDGE_FALLTHRU;
3955 /* Fix up edges that now fall through, or rather should now fall through
3956 but previously required a jump around now deleted blocks. Simplify
3957 the search by only examining blocks numerically adjacent, since this
3958 is how find_basic_blocks created them. */
3961 tidy_fallthru_edges ()
3965 for (i = 1; i < n_basic_blocks; ++i)
3967 basic_block b = BASIC_BLOCK (i - 1);
3968 basic_block c = BASIC_BLOCK (i);
3971 /* We care about simple conditional or unconditional jumps with
3974 If we had a conditional branch to the next instruction when
3975 find_basic_blocks was called, then there will only be one
3976 out edge for the block which ended with the conditional
3977 branch (since we do not create duplicate edges).
3979 Furthermore, the edge will be marked as a fallthru because we
3980 merge the flags for the duplicate edges. So we do not want to
3981 check that the edge is not a FALLTHRU edge. */
3982 if ((s = b->succ) != NULL
3983 && ! (s->flags & EDGE_COMPLEX)
3984 && s->succ_next == NULL
3986 /* If the jump insn has side effects, we can't tidy the edge. */
3987 && (GET_CODE (b->end) != JUMP_INSN
3988 || onlyjump_p (b->end)))
3989 tidy_fallthru_edge (s, b, c);
3993 /* Perform data flow analysis.
3994 F is the first insn of the function; FLAGS is a set of PROP_* flags
3995 to be used in accumulating flow info. */
3998 life_analysis (f, file, flags)
4003 #ifdef ELIMINABLE_REGS
4005 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
4008 /* Record which registers will be eliminated. We use this in
4011 CLEAR_HARD_REG_SET (elim_reg_set);
4013 #ifdef ELIMINABLE_REGS
4014 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
4015 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
4017 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
4021 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
4023 /* The post-reload life analysis have (on a global basis) the same
4024 registers live as was computed by reload itself. elimination
4025 Otherwise offsets and such may be incorrect.
4027 Reload will make some registers as live even though they do not
4030 We don't want to create new auto-incs after reload, since they
4031 are unlikely to be useful and can cause problems with shared
4033 if (reload_completed)
4034 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
4036 /* We want alias analysis information for local dead store elimination. */
4037 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4038 init_alias_analysis ();
4040 /* Always remove no-op moves. Do this before other processing so
4041 that we don't have to keep re-scanning them. */
4042 delete_noop_moves (f);
4044 /* Some targets can emit simpler epilogues if they know that sp was
4045 not ever modified during the function. After reload, of course,
4046 we've already emitted the epilogue so there's no sense searching. */
4047 if (! reload_completed)
4048 notice_stack_pointer_modification (f);
4050 /* Allocate and zero out data structures that will record the
4051 data from lifetime analysis. */
4052 allocate_reg_life_data ();
4053 allocate_bb_life_data ();
4055 /* Find the set of registers live on function exit. */
4056 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
4058 /* "Update" life info from zero. It'd be nice to begin the
4059 relaxation with just the exit and noreturn blocks, but that set
4060 is not immediately handy. */
4062 if (flags & PROP_REG_INFO)
4063 memset (regs_ever_live, 0, sizeof (regs_ever_live));
4064 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
4067 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4068 end_alias_analysis ();
4071 dump_flow_info (file);
4073 free_basic_block_vars (1);
4075 #ifdef ENABLE_CHECKING
4079 /* Search for any REG_LABEL notes which reference deleted labels. */
4080 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4082 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4084 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
4091 /* A subroutine of verify_wide_reg, called through for_each_rtx.
4092 Search for REGNO. If found, abort if it is not wider than word_mode. */
4095 verify_wide_reg_1 (px, pregno)
4100 unsigned int regno = *(int *) pregno;
4102 if (GET_CODE (x) == REG && REGNO (x) == regno)
4104 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
4111 /* A subroutine of verify_local_live_at_start. Search through insns
4112 between HEAD and END looking for register REGNO. */
4115 verify_wide_reg (regno, head, end)
4122 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
4126 head = NEXT_INSN (head);
4129 /* We didn't find the register at all. Something's way screwy. */
4131 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
4132 print_rtl_and_abort ();
4135 /* A subroutine of update_life_info. Verify that there are no untoward
4136 changes in live_at_start during a local update. */
4139 verify_local_live_at_start (new_live_at_start, bb)
4140 regset new_live_at_start;
4143 if (reload_completed)
4145 /* After reload, there are no pseudos, nor subregs of multi-word
4146 registers. The regsets should exactly match. */
4147 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
4151 fprintf (rtl_dump_file,
4152 "live_at_start mismatch in bb %d, aborting\n",
4154 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
4155 debug_bitmap_file (rtl_dump_file, new_live_at_start);
4157 print_rtl_and_abort ();
4164 /* Find the set of changed registers. */
4165 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
4167 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
4169 /* No registers should die. */
4170 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
4173 fprintf (rtl_dump_file,
4174 "Register %d died unexpectedly in block %d\n", i,
4176 print_rtl_and_abort ();
4179 /* Verify that the now-live register is wider than word_mode. */
4180 verify_wide_reg (i, bb->head, bb->end);
4185 /* Updates life information starting with the basic blocks set in BLOCKS.
4186 If BLOCKS is null, consider it to be the universal set.
4188 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
4189 we are only expecting local modifications to basic blocks. If we find
4190 extra registers live at the beginning of a block, then we either killed
4191 useful data, or we have a broken split that wants data not provided.
4192 If we find registers removed from live_at_start, that means we have
4193 a broken peephole that is killing a register it shouldn't.
4195 ??? This is not true in one situation -- when a pre-reload splitter
4196 generates subregs of a multi-word pseudo, current life analysis will
4197 lose the kill. So we _can_ have a pseudo go live. How irritating.
4199 Including PROP_REG_INFO does not properly refresh regs_ever_live
4200 unless the caller resets it to zero. */
4203 update_life_info (blocks, extent, prop_flags)
4205 enum update_life_extent extent;
4209 regset_head tmp_head;
4212 tmp = INITIALIZE_REG_SET (tmp_head);
4214 /* For a global update, we go through the relaxation process again. */
4215 if (extent != UPDATE_LIFE_LOCAL)
4217 calculate_global_regs_live (blocks, blocks,
4218 prop_flags & PROP_SCAN_DEAD_CODE);
4220 /* If asked, remove notes from the blocks we'll update. */
4221 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
4222 count_or_remove_death_notes (blocks, 1);
4227 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4229 basic_block bb = BASIC_BLOCK (i);
4231 COPY_REG_SET (tmp, bb->global_live_at_end);
4232 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4234 if (extent == UPDATE_LIFE_LOCAL)
4235 verify_local_live_at_start (tmp, bb);
4240 for (i = n_basic_blocks - 1; i >= 0; --i)
4242 basic_block bb = BASIC_BLOCK (i);
4244 COPY_REG_SET (tmp, bb->global_live_at_end);
4245 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4247 if (extent == UPDATE_LIFE_LOCAL)
4248 verify_local_live_at_start (tmp, bb);
4254 if (prop_flags & PROP_REG_INFO)
4256 /* The only pseudos that are live at the beginning of the function
4257 are those that were not set anywhere in the function. local-alloc
4258 doesn't know how to handle these correctly, so mark them as not
4259 local to any one basic block. */
4260 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
4261 FIRST_PSEUDO_REGISTER, i,
4262 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4264 /* We have a problem with any pseudoreg that lives across the setjmp.
4265 ANSI says that if a user variable does not change in value between
4266 the setjmp and the longjmp, then the longjmp preserves it. This
4267 includes longjmp from a place where the pseudo appears dead.
4268 (In principle, the value still exists if it is in scope.)
4269 If the pseudo goes in a hard reg, some other value may occupy
4270 that hard reg where this pseudo is dead, thus clobbering the pseudo.
4271 Conclusion: such a pseudo must not go in a hard reg. */
4272 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
4273 FIRST_PSEUDO_REGISTER, i,
4275 if (regno_reg_rtx[i] != 0)
4277 REG_LIVE_LENGTH (i) = -1;
4278 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4284 /* Free the variables allocated by find_basic_blocks.
4286 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
4289 free_basic_block_vars (keep_head_end_p)
4290 int keep_head_end_p;
4292 if (basic_block_for_insn)
4294 VARRAY_FREE (basic_block_for_insn);
4295 basic_block_for_insn = NULL;
4298 if (! keep_head_end_p)
4300 if (basic_block_info)
4303 VARRAY_FREE (basic_block_info);
4307 ENTRY_BLOCK_PTR->aux = NULL;
4308 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
4309 EXIT_BLOCK_PTR->aux = NULL;
4310 EXIT_BLOCK_PTR->global_live_at_start = NULL;
4314 /* Delete any insns that copy a register to itself. */
4317 delete_noop_moves (f)
4318 rtx f ATTRIBUTE_UNUSED;
4324 for (i = 0; i < n_basic_blocks; i++)
4326 bb = BASIC_BLOCK (i);
4327 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
4329 next = NEXT_INSN (insn);
4330 if (INSN_P (insn) && noop_move_p (insn))
4332 /* Do not call flow_delete_insn here to not confuse backward
4333 pointers of LIBCALL block. */
4334 PUT_CODE (insn, NOTE);
4335 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
4336 NOTE_SOURCE_FILE (insn) = 0;
4342 /* Determine if the stack pointer is constant over the life of the function.
4343 Only useful before prologues have been emitted. */
4346 notice_stack_pointer_modification_1 (x, pat, data)
4348 rtx pat ATTRIBUTE_UNUSED;
4349 void *data ATTRIBUTE_UNUSED;
4351 if (x == stack_pointer_rtx
4352 /* The stack pointer is only modified indirectly as the result
4353 of a push until later in flow. See the comments in rtl.texi
4354 regarding Embedded Side-Effects on Addresses. */
4355 || (GET_CODE (x) == MEM
4356 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
4357 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
4358 current_function_sp_is_unchanging = 0;
4362 notice_stack_pointer_modification (f)
4367 /* Assume that the stack pointer is unchanging if alloca hasn't
4369 current_function_sp_is_unchanging = !current_function_calls_alloca;
4370 if (! current_function_sp_is_unchanging)
4373 for (insn = f; insn; insn = NEXT_INSN (insn))
4377 /* Check if insn modifies the stack pointer. */
4378 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
4380 if (! current_function_sp_is_unchanging)
4386 /* Mark a register in SET. Hard registers in large modes get all
4387 of their component registers set as well. */
4390 mark_reg (reg, xset)
4394 regset set = (regset) xset;
4395 int regno = REGNO (reg);
4397 if (GET_MODE (reg) == BLKmode)
4400 SET_REGNO_REG_SET (set, regno);
4401 if (regno < FIRST_PSEUDO_REGISTER)
4403 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
4405 SET_REGNO_REG_SET (set, regno + n);
4409 /* Mark those regs which are needed at the end of the function as live
4410 at the end of the last basic block. */
4413 mark_regs_live_at_end (set)
4418 /* If exiting needs the right stack value, consider the stack pointer
4419 live at the end of the function. */
4420 if ((HAVE_epilogue && reload_completed)
4421 || ! EXIT_IGNORE_STACK
4422 || (! FRAME_POINTER_REQUIRED
4423 && ! current_function_calls_alloca
4424 && flag_omit_frame_pointer)
4425 || current_function_sp_is_unchanging)
4427 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
4430 /* Mark the frame pointer if needed at the end of the function. If
4431 we end up eliminating it, it will be removed from the live list
4432 of each basic block by reload. */
4434 if (! reload_completed || frame_pointer_needed)
4436 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
4437 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4438 /* If they are different, also mark the hard frame pointer as live. */
4439 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
4440 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
4444 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
4445 /* Many architectures have a GP register even without flag_pic.
4446 Assume the pic register is not in use, or will be handled by
4447 other means, if it is not fixed. */
4448 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4449 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4450 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
4453 /* Mark all global registers, and all registers used by the epilogue
4454 as being live at the end of the function since they may be
4455 referenced by our caller. */
4456 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4457 if (global_regs[i] || EPILOGUE_USES (i))
4458 SET_REGNO_REG_SET (set, i);
4460 if (HAVE_epilogue && reload_completed)
4462 /* Mark all call-saved registers that we actually used. */
4463 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4464 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
4465 SET_REGNO_REG_SET (set, i);
4468 #ifdef EH_RETURN_DATA_REGNO
4469 /* Mark the registers that will contain data for the handler. */
4470 if (reload_completed && current_function_calls_eh_return)
4473 unsigned regno = EH_RETURN_DATA_REGNO(i);
4474 if (regno == INVALID_REGNUM)
4476 SET_REGNO_REG_SET (set, regno);
4479 #ifdef EH_RETURN_STACKADJ_RTX
4480 if ((! HAVE_epilogue || ! reload_completed)
4481 && current_function_calls_eh_return)
4483 rtx tmp = EH_RETURN_STACKADJ_RTX;
4484 if (tmp && REG_P (tmp))
4485 mark_reg (tmp, set);
4488 #ifdef EH_RETURN_HANDLER_RTX
4489 if ((! HAVE_epilogue || ! reload_completed)
4490 && current_function_calls_eh_return)
4492 rtx tmp = EH_RETURN_HANDLER_RTX;
4493 if (tmp && REG_P (tmp))
4494 mark_reg (tmp, set);
4498 /* Mark function return value. */
4499 diddle_return_value (mark_reg, set);
4502 /* Callback function for for_each_successor_phi. DATA is a regset.
4503 Sets the SRC_REGNO, the regno of the phi alternative for phi node
4504 INSN, in the regset. */
4507 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
4508 rtx insn ATTRIBUTE_UNUSED;
4509 int dest_regno ATTRIBUTE_UNUSED;
4513 regset live = (regset) data;
4514 SET_REGNO_REG_SET (live, src_regno);
4518 /* Propagate global life info around the graph of basic blocks. Begin
4519 considering blocks with their corresponding bit set in BLOCKS_IN.
4520 If BLOCKS_IN is null, consider it the universal set.
4522 BLOCKS_OUT is set for every block that was changed. */
4525 calculate_global_regs_live (blocks_in, blocks_out, flags)
4526 sbitmap blocks_in, blocks_out;
4529 basic_block *queue, *qhead, *qtail, *qend;
4530 regset tmp, new_live_at_end, call_used;
4531 regset_head tmp_head, call_used_head;
4532 regset_head new_live_at_end_head;
4535 tmp = INITIALIZE_REG_SET (tmp_head);
4536 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
4537 call_used = INITIALIZE_REG_SET (call_used_head);
4539 /* Inconveniently, this is only redily available in hard reg set form. */
4540 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
4541 if (call_used_regs[i])
4542 SET_REGNO_REG_SET (call_used, i);
4544 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
4545 because the `head == tail' style test for an empty queue doesn't
4546 work with a full queue. */
4547 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
4549 qhead = qend = queue + n_basic_blocks + 2;
4551 /* Queue the blocks set in the initial mask. Do this in reverse block
4552 number order so that we are more likely for the first round to do
4553 useful work. We use AUX non-null to flag that the block is queued. */
4556 /* Clear out the garbage that might be hanging out in bb->aux. */
4557 for (i = n_basic_blocks - 1; i >= 0; --i)
4558 BASIC_BLOCK (i)->aux = NULL;
4560 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
4562 basic_block bb = BASIC_BLOCK (i);
4569 for (i = 0; i < n_basic_blocks; ++i)
4571 basic_block bb = BASIC_BLOCK (i);
4578 sbitmap_zero (blocks_out);
4580 /* We work through the queue until there are no more blocks. What
4581 is live at the end of this block is precisely the union of what
4582 is live at the beginning of all its successors. So, we set its
4583 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
4584 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
4585 this block by walking through the instructions in this block in
4586 reverse order and updating as we go. If that changed
4587 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
4588 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
4590 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
4591 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
4592 must either be live at the end of the block, or used within the
4593 block. In the latter case, it will certainly never disappear
4594 from GLOBAL_LIVE_AT_START. In the former case, the register
4595 could go away only if it disappeared from GLOBAL_LIVE_AT_START
4596 for one of the successor blocks. By induction, that cannot
4598 while (qhead != qtail)
4600 int rescan, changed;
4609 /* Begin by propagating live_at_start from the successor blocks. */
4610 CLEAR_REG_SET (new_live_at_end);
4611 for (e = bb->succ; e; e = e->succ_next)
4613 basic_block sb = e->dest;
4615 /* Call-clobbered registers die across exception and call edges. */
4616 /* ??? Abnormal call edges ignored for the moment, as this gets
4617 confused by sibling call edges, which crashes reg-stack. */
4618 if (e->flags & EDGE_EH)
4620 bitmap_operation (tmp, sb->global_live_at_start,
4621 call_used, BITMAP_AND_COMPL);
4622 IOR_REG_SET (new_live_at_end, tmp);
4625 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
4628 /* The all-important stack pointer must always be live. */
4629 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
4631 /* Before reload, there are a few registers that must be forced
4632 live everywhere -- which might not already be the case for
4633 blocks within infinite loops. */
4634 if (! reload_completed)
4636 /* Any reference to any pseudo before reload is a potential
4637 reference of the frame pointer. */
4638 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
4640 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4641 /* Pseudos with argument area equivalences may require
4642 reloading via the argument pointer. */
4643 if (fixed_regs[ARG_POINTER_REGNUM])
4644 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
4647 /* Any constant, or pseudo with constant equivalences, may
4648 require reloading from memory using the pic register. */
4649 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4650 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4651 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
4654 /* Regs used in phi nodes are not included in
4655 global_live_at_start, since they are live only along a
4656 particular edge. Set those regs that are live because of a
4657 phi node alternative corresponding to this particular block. */
4659 for_each_successor_phi (bb, &set_phi_alternative_reg,
4662 if (bb == ENTRY_BLOCK_PTR)
4664 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4668 /* On our first pass through this block, we'll go ahead and continue.
4669 Recognize first pass by local_set NULL. On subsequent passes, we
4670 get to skip out early if live_at_end wouldn't have changed. */
4672 if (bb->local_set == NULL)
4674 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4675 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4680 /* If any bits were removed from live_at_end, we'll have to
4681 rescan the block. This wouldn't be necessary if we had
4682 precalculated local_live, however with PROP_SCAN_DEAD_CODE
4683 local_live is really dependent on live_at_end. */
4684 CLEAR_REG_SET (tmp);
4685 rescan = bitmap_operation (tmp, bb->global_live_at_end,
4686 new_live_at_end, BITMAP_AND_COMPL);
4690 /* If any of the registers in the new live_at_end set are
4691 conditionally set in this basic block, we must rescan.
4692 This is because conditional lifetimes at the end of the
4693 block do not just take the live_at_end set into account,
4694 but also the liveness at the start of each successor
4695 block. We can miss changes in those sets if we only
4696 compare the new live_at_end against the previous one. */
4697 CLEAR_REG_SET (tmp);
4698 rescan = bitmap_operation (tmp, new_live_at_end,
4699 bb->cond_local_set, BITMAP_AND);
4704 /* Find the set of changed bits. Take this opportunity
4705 to notice that this set is empty and early out. */
4706 CLEAR_REG_SET (tmp);
4707 changed = bitmap_operation (tmp, bb->global_live_at_end,
4708 new_live_at_end, BITMAP_XOR);
4712 /* If any of the changed bits overlap with local_set,
4713 we'll have to rescan the block. Detect overlap by
4714 the AND with ~local_set turning off bits. */
4715 rescan = bitmap_operation (tmp, tmp, bb->local_set,
4720 /* Let our caller know that BB changed enough to require its
4721 death notes updated. */
4723 SET_BIT (blocks_out, bb->index);
4727 /* Add to live_at_start the set of all registers in
4728 new_live_at_end that aren't in the old live_at_end. */
4730 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
4732 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4734 changed = bitmap_operation (bb->global_live_at_start,
4735 bb->global_live_at_start,
4742 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4744 /* Rescan the block insn by insn to turn (a copy of) live_at_end
4745 into live_at_start. */
4746 propagate_block (bb, new_live_at_end, bb->local_set,
4747 bb->cond_local_set, flags);
4749 /* If live_at start didn't change, no need to go farther. */
4750 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
4753 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
4756 /* Queue all predecessors of BB so that we may re-examine
4757 their live_at_end. */
4758 for (e = bb->pred; e; e = e->pred_next)
4760 basic_block pb = e->src;
4761 if (pb->aux == NULL)
4772 FREE_REG_SET (new_live_at_end);
4773 FREE_REG_SET (call_used);
4777 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
4779 basic_block bb = BASIC_BLOCK (i);
4780 FREE_REG_SET (bb->local_set);
4781 FREE_REG_SET (bb->cond_local_set);
4786 for (i = n_basic_blocks - 1; i >= 0; --i)
4788 basic_block bb = BASIC_BLOCK (i);
4789 FREE_REG_SET (bb->local_set);
4790 FREE_REG_SET (bb->cond_local_set);
4797 /* Subroutines of life analysis. */
4799 /* Allocate the permanent data structures that represent the results
4800 of life analysis. Not static since used also for stupid life analysis. */
4803 allocate_bb_life_data ()
4807 for (i = 0; i < n_basic_blocks; i++)
4809 basic_block bb = BASIC_BLOCK (i);
4811 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4812 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4815 ENTRY_BLOCK_PTR->global_live_at_end
4816 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4817 EXIT_BLOCK_PTR->global_live_at_start
4818 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4820 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4824 allocate_reg_life_data ()
4828 max_regno = max_reg_num ();
4830 /* Recalculate the register space, in case it has grown. Old style
4831 vector oriented regsets would set regset_{size,bytes} here also. */
4832 allocate_reg_info (max_regno, FALSE, FALSE);
4834 /* Reset all the data we'll collect in propagate_block and its
4836 for (i = 0; i < max_regno; i++)
4840 REG_N_DEATHS (i) = 0;
4841 REG_N_CALLS_CROSSED (i) = 0;
4842 REG_LIVE_LENGTH (i) = 0;
4843 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4847 /* Delete dead instructions for propagate_block. */
4850 propagate_block_delete_insn (bb, insn)
4854 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4856 /* If the insn referred to a label, and that label was attached to
4857 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
4858 pretty much mandatory to delete it, because the ADDR_VEC may be
4859 referencing labels that no longer exist.
4861 INSN may reference a deleted label, particularly when a jump
4862 table has been optimized into a direct jump. There's no
4863 real good way to fix up the reference to the deleted label
4864 when the label is deleted, so we just allow it here.
4866 After dead code elimination is complete, we do search for
4867 any REG_LABEL notes which reference deleted labels as a
4870 if (inote && GET_CODE (inote) == CODE_LABEL)
4872 rtx label = XEXP (inote, 0);
4875 /* The label may be forced if it has been put in the constant
4876 pool. If that is the only use we must discard the table
4877 jump following it, but not the label itself. */
4878 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
4879 && (next = next_nonnote_insn (label)) != NULL
4880 && GET_CODE (next) == JUMP_INSN
4881 && (GET_CODE (PATTERN (next)) == ADDR_VEC
4882 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
4884 rtx pat = PATTERN (next);
4885 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4886 int len = XVECLEN (pat, diff_vec_p);
4889 for (i = 0; i < len; i++)
4890 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
4892 flow_delete_insn (next);
4896 if (bb->end == insn)
4897 bb->end = PREV_INSN (insn);
4898 flow_delete_insn (insn);
4901 /* Delete dead libcalls for propagate_block. Return the insn
4902 before the libcall. */
4905 propagate_block_delete_libcall (bb, insn, note)
4909 rtx first = XEXP (note, 0);
4910 rtx before = PREV_INSN (first);
4912 if (insn == bb->end)
4915 flow_delete_insn_chain (first, insn);
4919 /* Update the life-status of regs for one insn. Return the previous insn. */
4922 propagate_one_insn (pbi, insn)
4923 struct propagate_block_info *pbi;
4926 rtx prev = PREV_INSN (insn);
4927 int flags = pbi->flags;
4928 int insn_is_dead = 0;
4929 int libcall_is_dead = 0;
4933 if (! INSN_P (insn))
4936 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
4937 if (flags & PROP_SCAN_DEAD_CODE)
4939 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
4940 libcall_is_dead = (insn_is_dead && note != 0
4941 && libcall_dead_p (pbi, note, insn));
4944 /* If an instruction consists of just dead store(s) on final pass,
4946 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
4948 /* If we're trying to delete a prologue or epilogue instruction
4949 that isn't flagged as possibly being dead, something is wrong.
4950 But if we are keeping the stack pointer depressed, we might well
4951 be deleting insns that are used to compute the amount to update
4952 it by, so they are fine. */
4953 if (reload_completed
4954 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4955 && (TYPE_RETURNS_STACK_DEPRESSED
4956 (TREE_TYPE (current_function_decl))))
4957 && (((HAVE_epilogue || HAVE_prologue)
4958 && prologue_epilogue_contains (insn))
4959 || (HAVE_sibcall_epilogue
4960 && sibcall_epilogue_contains (insn)))
4961 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
4964 /* Record sets. Do this even for dead instructions, since they
4965 would have killed the values if they hadn't been deleted. */
4966 mark_set_regs (pbi, PATTERN (insn), insn);
4968 /* CC0 is now known to be dead. Either this insn used it,
4969 in which case it doesn't anymore, or clobbered it,
4970 so the next insn can't use it. */
4973 if (libcall_is_dead)
4974 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
4976 propagate_block_delete_insn (pbi->bb, insn);
4981 /* See if this is an increment or decrement that can be merged into
4982 a following memory address. */
4985 register rtx x = single_set (insn);
4987 /* Does this instruction increment or decrement a register? */
4988 if ((flags & PROP_AUTOINC)
4990 && GET_CODE (SET_DEST (x)) == REG
4991 && (GET_CODE (SET_SRC (x)) == PLUS
4992 || GET_CODE (SET_SRC (x)) == MINUS)
4993 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
4994 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
4995 /* Ok, look for a following memory ref we can combine with.
4996 If one is found, change the memory ref to a PRE_INC
4997 or PRE_DEC, cancel this insn, and return 1.
4998 Return 0 if nothing has been done. */
4999 && try_pre_increment_1 (pbi, insn))
5002 #endif /* AUTO_INC_DEC */
5004 CLEAR_REG_SET (pbi->new_set);
5006 /* If this is not the final pass, and this insn is copying the value of
5007 a library call and it's dead, don't scan the insns that perform the
5008 library call, so that the call's arguments are not marked live. */
5009 if (libcall_is_dead)
5011 /* Record the death of the dest reg. */
5012 mark_set_regs (pbi, PATTERN (insn), insn);
5014 insn = XEXP (note, 0);
5015 return PREV_INSN (insn);
5017 else if (GET_CODE (PATTERN (insn)) == SET
5018 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
5019 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
5020 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
5021 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
5022 /* We have an insn to pop a constant amount off the stack.
5023 (Such insns use PLUS regardless of the direction of the stack,
5024 and any insn to adjust the stack by a constant is always a pop.)
5025 These insns, if not dead stores, have no effect on life. */
5029 /* Any regs live at the time of a call instruction must not go
5030 in a register clobbered by calls. Find all regs now live and
5031 record this for them. */
5033 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
5034 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5035 { REG_N_CALLS_CROSSED (i)++; });
5037 /* Record sets. Do this even for dead instructions, since they
5038 would have killed the values if they hadn't been deleted. */
5039 mark_set_regs (pbi, PATTERN (insn), insn);
5041 if (GET_CODE (insn) == CALL_INSN)
5047 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5048 cond = COND_EXEC_TEST (PATTERN (insn));
5050 /* Non-constant calls clobber memory. */
5051 if (! CONST_CALL_P (insn))
5053 free_EXPR_LIST_list (&pbi->mem_set_list);
5054 pbi->mem_set_list_len = 0;
5057 /* There may be extra registers to be clobbered. */
5058 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5060 note = XEXP (note, 1))
5061 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
5062 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
5063 cond, insn, pbi->flags);
5065 /* Calls change all call-used and global registers. */
5066 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5067 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
5069 /* We do not want REG_UNUSED notes for these registers. */
5070 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
5072 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
5076 /* If an insn doesn't use CC0, it becomes dead since we assume
5077 that every insn clobbers it. So show it dead here;
5078 mark_used_regs will set it live if it is referenced. */
5083 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
5085 /* Sometimes we may have inserted something before INSN (such as a move)
5086 when we make an auto-inc. So ensure we will scan those insns. */
5088 prev = PREV_INSN (insn);
5091 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
5097 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5098 cond = COND_EXEC_TEST (PATTERN (insn));
5100 /* Calls use their arguments. */
5101 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5103 note = XEXP (note, 1))
5104 if (GET_CODE (XEXP (note, 0)) == USE)
5105 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
5108 /* The stack ptr is used (honorarily) by a CALL insn. */
5109 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
5111 /* Calls may also reference any of the global registers,
5112 so they are made live. */
5113 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5115 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
5120 /* On final pass, update counts of how many insns in which each reg
5122 if (flags & PROP_REG_INFO)
5123 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5124 { REG_LIVE_LENGTH (i)++; });
5129 /* Initialize a propagate_block_info struct for public consumption.
5130 Note that the structure itself is opaque to this file, but that
5131 the user can use the regsets provided here. */
5133 struct propagate_block_info *
5134 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
5136 regset live, local_set, cond_local_set;
5139 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
5142 pbi->reg_live = live;
5143 pbi->mem_set_list = NULL_RTX;
5144 pbi->mem_set_list_len = 0;
5145 pbi->local_set = local_set;
5146 pbi->cond_local_set = cond_local_set;
5150 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5151 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
5153 pbi->reg_next_use = NULL;
5155 pbi->new_set = BITMAP_XMALLOC ();
5157 #ifdef HAVE_conditional_execution
5158 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
5159 free_reg_cond_life_info);
5160 pbi->reg_cond_reg = BITMAP_XMALLOC ();
5162 /* If this block ends in a conditional branch, for each register live
5163 from one side of the branch and not the other, record the register
5164 as conditionally dead. */
5165 if (GET_CODE (bb->end) == JUMP_INSN
5166 && any_condjump_p (bb->end))
5168 regset_head diff_head;
5169 regset diff = INITIALIZE_REG_SET (diff_head);
5170 basic_block bb_true, bb_false;
5171 rtx cond_true, cond_false, set_src;
5174 /* Identify the successor blocks. */
5175 bb_true = bb->succ->dest;
5176 if (bb->succ->succ_next != NULL)
5178 bb_false = bb->succ->succ_next->dest;
5180 if (bb->succ->flags & EDGE_FALLTHRU)
5182 basic_block t = bb_false;
5186 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
5191 /* This can happen with a conditional jump to the next insn. */
5192 if (JUMP_LABEL (bb->end) != bb_true->head)
5195 /* Simplest way to do nothing. */
5199 /* Extract the condition from the branch. */
5200 set_src = SET_SRC (pc_set (bb->end));
5201 cond_true = XEXP (set_src, 0);
5202 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
5203 GET_MODE (cond_true), XEXP (cond_true, 0),
5204 XEXP (cond_true, 1));
5205 if (GET_CODE (XEXP (set_src, 1)) == PC)
5208 cond_false = cond_true;
5212 /* Compute which register lead different lives in the successors. */
5213 if (bitmap_operation (diff, bb_true->global_live_at_start,
5214 bb_false->global_live_at_start, BITMAP_XOR))
5216 rtx reg = XEXP (cond_true, 0);
5218 if (GET_CODE (reg) == SUBREG)
5219 reg = SUBREG_REG (reg);
5221 if (GET_CODE (reg) != REG)
5224 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
5226 /* For each such register, mark it conditionally dead. */
5227 EXECUTE_IF_SET_IN_REG_SET
5230 struct reg_cond_life_info *rcli;
5233 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5235 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
5239 rcli->condition = cond;
5240 rcli->stores = const0_rtx;
5241 rcli->orig_condition = cond;
5243 splay_tree_insert (pbi->reg_cond_dead, i,
5244 (splay_tree_value) rcli);
5248 FREE_REG_SET (diff);
5252 /* If this block has no successors, any stores to the frame that aren't
5253 used later in the block are dead. So make a pass over the block
5254 recording any such that are made and show them dead at the end. We do
5255 a very conservative and simple job here. */
5257 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
5258 && (TYPE_RETURNS_STACK_DEPRESSED
5259 (TREE_TYPE (current_function_decl))))
5260 && (flags & PROP_SCAN_DEAD_CODE)
5261 && (bb->succ == NULL
5262 || (bb->succ->succ_next == NULL
5263 && bb->succ->dest == EXIT_BLOCK_PTR
5264 && ! current_function_calls_eh_return)))
5267 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
5268 if (GET_CODE (insn) == INSN
5269 && (set = single_set (insn))
5270 && GET_CODE (SET_DEST (set)) == MEM)
5272 rtx mem = SET_DEST (set);
5273 rtx canon_mem = canon_rtx (mem);
5275 /* This optimization is performed by faking a store to the
5276 memory at the end of the block. This doesn't work for
5277 unchanging memories because multiple stores to unchanging
5278 memory is illegal and alias analysis doesn't consider it. */
5279 if (RTX_UNCHANGING_P (canon_mem))
5282 if (XEXP (canon_mem, 0) == frame_pointer_rtx
5283 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
5284 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
5285 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
5288 /* Store a copy of mem, otherwise the address may be scrogged
5289 by find_auto_inc. This matters because insn_dead_p uses
5290 an rtx_equal_p check to determine if two addresses are
5291 the same. This works before find_auto_inc, but fails
5292 after find_auto_inc, causing discrepencies between the
5293 set of live registers calculated during the
5294 calculate_global_regs_live phase and what actually exists
5295 after flow completes, leading to aborts. */
5296 if (flags & PROP_AUTOINC)
5297 mem = shallow_copy_rtx (mem);
5299 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
5300 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
5309 /* Release a propagate_block_info struct. */
5312 free_propagate_block_info (pbi)
5313 struct propagate_block_info *pbi;
5315 free_EXPR_LIST_list (&pbi->mem_set_list);
5317 BITMAP_XFREE (pbi->new_set);
5319 #ifdef HAVE_conditional_execution
5320 splay_tree_delete (pbi->reg_cond_dead);
5321 BITMAP_XFREE (pbi->reg_cond_reg);
5324 if (pbi->reg_next_use)
5325 free (pbi->reg_next_use);
5330 /* Compute the registers live at the beginning of a basic block BB from
5331 those live at the end.
5333 When called, REG_LIVE contains those live at the end. On return, it
5334 contains those live at the beginning.
5336 LOCAL_SET, if non-null, will be set with all registers killed
5337 unconditionally by this basic block.
5338 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
5339 killed conditionally by this basic block. If there is any unconditional
5340 set of a register, then the corresponding bit will be set in LOCAL_SET
5341 and cleared in COND_LOCAL_SET.
5342 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
5343 case, the resulting set will be equal to the union of the two sets that
5344 would otherwise be computed. */
5347 propagate_block (bb, live, local_set, cond_local_set, flags)
5351 regset cond_local_set;
5354 struct propagate_block_info *pbi;
5357 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
5359 if (flags & PROP_REG_INFO)
5363 /* Process the regs live at the end of the block.
5364 Mark them as not local to any one basic block. */
5365 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
5366 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
5369 /* Scan the block an insn at a time from end to beginning. */
5371 for (insn = bb->end;; insn = prev)
5373 /* If this is a call to `setjmp' et al, warn if any
5374 non-volatile datum is live. */
5375 if ((flags & PROP_REG_INFO)
5376 && GET_CODE (insn) == NOTE
5377 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
5378 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
5380 prev = propagate_one_insn (pbi, insn);
5382 if (insn == bb->head)
5386 free_propagate_block_info (pbi);
5389 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
5390 (SET expressions whose destinations are registers dead after the insn).
5391 NEEDED is the regset that says which regs are alive after the insn.
5393 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
5395 If X is the entire body of an insn, NOTES contains the reg notes
5396 pertaining to the insn. */
5399 insn_dead_p (pbi, x, call_ok, notes)
5400 struct propagate_block_info *pbi;
5403 rtx notes ATTRIBUTE_UNUSED;
5405 enum rtx_code code = GET_CODE (x);
5408 /* If flow is invoked after reload, we must take existing AUTO_INC
5409 expresions into account. */
5410 if (reload_completed)
5412 for (; notes; notes = XEXP (notes, 1))
5414 if (REG_NOTE_KIND (notes) == REG_INC)
5416 int regno = REGNO (XEXP (notes, 0));
5418 /* Don't delete insns to set global regs. */
5419 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5420 || REGNO_REG_SET_P (pbi->reg_live, regno))
5427 /* If setting something that's a reg or part of one,
5428 see if that register's altered value will be live. */
5432 rtx r = SET_DEST (x);
5435 if (GET_CODE (r) == CC0)
5436 return ! pbi->cc0_live;
5439 /* A SET that is a subroutine call cannot be dead. */
5440 if (GET_CODE (SET_SRC (x)) == CALL)
5446 /* Don't eliminate loads from volatile memory or volatile asms. */
5447 else if (volatile_refs_p (SET_SRC (x)))
5450 if (GET_CODE (r) == MEM)
5454 if (MEM_VOLATILE_P (r))
5457 /* Walk the set of memory locations we are currently tracking
5458 and see if one is an identical match to this memory location.
5459 If so, this memory write is dead (remember, we're walking
5460 backwards from the end of the block to the start). Since
5461 rtx_equal_p does not check the alias set or flags, we also
5462 must have the potential for them to conflict (anti_dependence). */
5463 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
5464 if (anti_dependence (r, XEXP (temp, 0)))
5466 rtx mem = XEXP (temp, 0);
5468 if (rtx_equal_p (mem, r))
5471 /* Check if memory reference matches an auto increment. Only
5472 post increment/decrement or modify are valid. */
5473 if (GET_MODE (mem) == GET_MODE (r)
5474 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
5475 || GET_CODE (XEXP (mem, 0)) == POST_INC
5476 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
5477 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
5478 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
5485 while (GET_CODE (r) == SUBREG
5486 || GET_CODE (r) == STRICT_LOW_PART
5487 || GET_CODE (r) == ZERO_EXTRACT)
5490 if (GET_CODE (r) == REG)
5492 int regno = REGNO (r);
5495 if (REGNO_REG_SET_P (pbi->reg_live, regno))
5498 /* If this is a hard register, verify that subsequent
5499 words are not needed. */
5500 if (regno < FIRST_PSEUDO_REGISTER)
5502 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
5505 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
5509 /* Don't delete insns to set global regs. */
5510 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5513 /* Make sure insns to set the stack pointer aren't deleted. */
5514 if (regno == STACK_POINTER_REGNUM)
5517 /* ??? These bits might be redundant with the force live bits
5518 in calculate_global_regs_live. We would delete from
5519 sequential sets; whether this actually affects real code
5520 for anything but the stack pointer I don't know. */
5521 /* Make sure insns to set the frame pointer aren't deleted. */
5522 if (regno == FRAME_POINTER_REGNUM
5523 && (! reload_completed || frame_pointer_needed))
5525 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5526 if (regno == HARD_FRAME_POINTER_REGNUM
5527 && (! reload_completed || frame_pointer_needed))
5531 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5532 /* Make sure insns to set arg pointer are never deleted
5533 (if the arg pointer isn't fixed, there will be a USE
5534 for it, so we can treat it normally). */
5535 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5539 /* Otherwise, the set is dead. */
5545 /* If performing several activities, insn is dead if each activity
5546 is individually dead. Also, CLOBBERs and USEs can be ignored; a
5547 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
5549 else if (code == PARALLEL)
5551 int i = XVECLEN (x, 0);
5553 for (i--; i >= 0; i--)
5554 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
5555 && GET_CODE (XVECEXP (x, 0, i)) != USE
5556 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
5562 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
5563 is not necessarily true for hard registers. */
5564 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
5565 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
5566 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
5569 /* We do not check other CLOBBER or USE here. An insn consisting of just
5570 a CLOBBER or just a USE should not be deleted. */
5574 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
5575 return 1 if the entire library call is dead.
5576 This is true if INSN copies a register (hard or pseudo)
5577 and if the hard return reg of the call insn is dead.
5578 (The caller should have tested the destination of the SET inside
5579 INSN already for death.)
5581 If this insn doesn't just copy a register, then we don't
5582 have an ordinary libcall. In that case, cse could not have
5583 managed to substitute the source for the dest later on,
5584 so we can assume the libcall is dead.
5586 PBI is the block info giving pseudoregs live before this insn.
5587 NOTE is the REG_RETVAL note of the insn. */
5590 libcall_dead_p (pbi, note, insn)
5591 struct propagate_block_info *pbi;
5595 rtx x = single_set (insn);
5599 register rtx r = SET_SRC (x);
5600 if (GET_CODE (r) == REG)
5602 rtx call = XEXP (note, 0);
5606 /* Find the call insn. */
5607 while (call != insn && GET_CODE (call) != CALL_INSN)
5608 call = NEXT_INSN (call);
5610 /* If there is none, do nothing special,
5611 since ordinary death handling can understand these insns. */
5615 /* See if the hard reg holding the value is dead.
5616 If this is a PARALLEL, find the call within it. */
5617 call_pat = PATTERN (call);
5618 if (GET_CODE (call_pat) == PARALLEL)
5620 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
5621 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
5622 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
5625 /* This may be a library call that is returning a value
5626 via invisible pointer. Do nothing special, since
5627 ordinary death handling can understand these insns. */
5631 call_pat = XVECEXP (call_pat, 0, i);
5634 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
5640 /* Return 1 if register REGNO was used before it was set, i.e. if it is
5641 live at function entry. Don't count global register variables, variables
5642 in registers that can be used for function arg passing, or variables in
5643 fixed hard registers. */
5646 regno_uninitialized (regno)
5649 if (n_basic_blocks == 0
5650 || (regno < FIRST_PSEUDO_REGISTER
5651 && (global_regs[regno]
5652 || fixed_regs[regno]
5653 || FUNCTION_ARG_REGNO_P (regno))))
5656 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
5659 /* 1 if register REGNO was alive at a place where `setjmp' was called
5660 and was set more than once or is an argument.
5661 Such regs may be clobbered by `longjmp'. */
5664 regno_clobbered_at_setjmp (regno)
5667 if (n_basic_blocks == 0)
5670 return ((REG_N_SETS (regno) > 1
5671 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
5672 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
5675 /* INSN references memory, possibly using autoincrement addressing modes.
5676 Find any entries on the mem_set_list that need to be invalidated due
5677 to an address change. */
5680 invalidate_mems_from_autoinc (pbi, insn)
5681 struct propagate_block_info *pbi;
5684 rtx note = REG_NOTES (insn);
5685 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
5687 if (REG_NOTE_KIND (note) == REG_INC)
5689 rtx temp = pbi->mem_set_list;
5690 rtx prev = NULL_RTX;
5695 next = XEXP (temp, 1);
5696 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
5698 /* Splice temp out of list. */
5700 XEXP (prev, 1) = next;
5702 pbi->mem_set_list = next;
5703 free_EXPR_LIST_node (temp);
5704 pbi->mem_set_list_len--;
5714 /* EXP is either a MEM or a REG. Remove any dependant entries
5715 from pbi->mem_set_list. */
5718 invalidate_mems_from_set (pbi, exp)
5719 struct propagate_block_info *pbi;
5722 rtx temp = pbi->mem_set_list;
5723 rtx prev = NULL_RTX;
5728 next = XEXP (temp, 1);
5729 if ((GET_CODE (exp) == MEM
5730 && output_dependence (XEXP (temp, 0), exp))
5731 || (GET_CODE (exp) == REG
5732 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
5734 /* Splice this entry out of the list. */
5736 XEXP (prev, 1) = next;
5738 pbi->mem_set_list = next;
5739 free_EXPR_LIST_node (temp);
5740 pbi->mem_set_list_len--;
5748 /* Process the registers that are set within X. Their bits are set to
5749 1 in the regset DEAD, because they are dead prior to this insn.
5751 If INSN is nonzero, it is the insn being processed.
5753 FLAGS is the set of operations to perform. */
5756 mark_set_regs (pbi, x, insn)
5757 struct propagate_block_info *pbi;
5760 rtx cond = NULL_RTX;
5765 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
5767 if (REG_NOTE_KIND (link) == REG_INC)
5768 mark_set_1 (pbi, SET, XEXP (link, 0),
5769 (GET_CODE (x) == COND_EXEC
5770 ? COND_EXEC_TEST (x) : NULL_RTX),
5774 switch (code = GET_CODE (x))
5778 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
5782 cond = COND_EXEC_TEST (x);
5783 x = COND_EXEC_CODE (x);
5789 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
5791 rtx sub = XVECEXP (x, 0, i);
5792 switch (code = GET_CODE (sub))
5795 if (cond != NULL_RTX)
5798 cond = COND_EXEC_TEST (sub);
5799 sub = COND_EXEC_CODE (sub);
5800 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
5806 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
5821 /* Process a single set, which appears in INSN. REG (which may not
5822 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
5823 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
5824 If the set is conditional (because it appear in a COND_EXEC), COND
5825 will be the condition. */
5828 mark_set_1 (pbi, code, reg, cond, insn, flags)
5829 struct propagate_block_info *pbi;
5831 rtx reg, cond, insn;
5834 int regno_first = -1, regno_last = -1;
5835 unsigned long not_dead = 0;
5838 /* Modifying just one hardware register of a multi-reg value or just a
5839 byte field of a register does not mean the value from before this insn
5840 is now dead. Of course, if it was dead after it's unused now. */
5842 switch (GET_CODE (reg))
5845 /* Some targets place small structures in registers for return values of
5846 functions. We have to detect this case specially here to get correct
5847 flow information. */
5848 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
5849 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
5850 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
5856 case STRICT_LOW_PART:
5857 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
5859 reg = XEXP (reg, 0);
5860 while (GET_CODE (reg) == SUBREG
5861 || GET_CODE (reg) == ZERO_EXTRACT
5862 || GET_CODE (reg) == SIGN_EXTRACT
5863 || GET_CODE (reg) == STRICT_LOW_PART);
5864 if (GET_CODE (reg) == MEM)
5866 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
5870 regno_last = regno_first = REGNO (reg);
5871 if (regno_first < FIRST_PSEUDO_REGISTER)
5872 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
5876 if (GET_CODE (SUBREG_REG (reg)) == REG)
5878 enum machine_mode outer_mode = GET_MODE (reg);
5879 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
5881 /* Identify the range of registers affected. This is moderately
5882 tricky for hard registers. See alter_subreg. */
5884 regno_last = regno_first = REGNO (SUBREG_REG (reg));
5885 if (regno_first < FIRST_PSEUDO_REGISTER)
5887 regno_first += subreg_regno_offset (regno_first, inner_mode,
5890 regno_last = (regno_first
5891 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
5893 /* Since we've just adjusted the register number ranges, make
5894 sure REG matches. Otherwise some_was_live will be clear
5895 when it shouldn't have been, and we'll create incorrect
5896 REG_UNUSED notes. */
5897 reg = gen_rtx_REG (outer_mode, regno_first);
5901 /* If the number of words in the subreg is less than the number
5902 of words in the full register, we have a well-defined partial
5903 set. Otherwise the high bits are undefined.
5905 This is only really applicable to pseudos, since we just took
5906 care of multi-word hard registers. */
5907 if (((GET_MODE_SIZE (outer_mode)
5908 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
5909 < ((GET_MODE_SIZE (inner_mode)
5910 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
5911 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
5914 reg = SUBREG_REG (reg);
5918 reg = SUBREG_REG (reg);
5925 /* If this set is a MEM, then it kills any aliased writes.
5926 If this set is a REG, then it kills any MEMs which use the reg. */
5927 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5929 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
5930 invalidate_mems_from_set (pbi, reg);
5932 /* If the memory reference had embedded side effects (autoincrement
5933 address modes. Then we may need to kill some entries on the
5935 if (insn && GET_CODE (reg) == MEM)
5936 invalidate_mems_from_autoinc (pbi, insn);
5938 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
5939 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
5940 /* ??? With more effort we could track conditional memory life. */
5942 /* We do not know the size of a BLKmode store, so we do not track
5943 them for redundant store elimination. */
5944 && GET_MODE (reg) != BLKmode
5945 /* There are no REG_INC notes for SP, so we can't assume we'll see
5946 everything that invalidates it. To be safe, don't eliminate any
5947 stores though SP; none of them should be redundant anyway. */
5948 && ! reg_mentioned_p (stack_pointer_rtx, reg))
5951 /* Store a copy of mem, otherwise the address may be
5952 scrogged by find_auto_inc. */
5953 if (flags & PROP_AUTOINC)
5954 reg = shallow_copy_rtx (reg);
5956 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
5957 pbi->mem_set_list_len++;
5961 if (GET_CODE (reg) == REG
5962 && ! (regno_first == FRAME_POINTER_REGNUM
5963 && (! reload_completed || frame_pointer_needed))
5964 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5965 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
5966 && (! reload_completed || frame_pointer_needed))
5968 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5969 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
5973 int some_was_live = 0, some_was_dead = 0;
5975 for (i = regno_first; i <= regno_last; ++i)
5977 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
5980 /* Order of the set operation matters here since both
5981 sets may be the same. */
5982 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
5983 if (cond != NULL_RTX
5984 && ! REGNO_REG_SET_P (pbi->local_set, i))
5985 SET_REGNO_REG_SET (pbi->cond_local_set, i);
5987 SET_REGNO_REG_SET (pbi->local_set, i);
5989 if (code != CLOBBER)
5990 SET_REGNO_REG_SET (pbi->new_set, i);
5992 some_was_live |= needed_regno;
5993 some_was_dead |= ! needed_regno;
5996 #ifdef HAVE_conditional_execution
5997 /* Consider conditional death in deciding that the register needs
5999 if (some_was_live && ! not_dead
6000 /* The stack pointer is never dead. Well, not strictly true,
6001 but it's very difficult to tell from here. Hopefully
6002 combine_stack_adjustments will fix up the most egregious
6004 && regno_first != STACK_POINTER_REGNUM)
6006 for (i = regno_first; i <= regno_last; ++i)
6007 if (! mark_regno_cond_dead (pbi, i, cond))
6008 not_dead |= ((unsigned long) 1) << (i - regno_first);
6012 /* Additional data to record if this is the final pass. */
6013 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
6014 | PROP_DEATH_NOTES | PROP_AUTOINC))
6017 register int blocknum = pbi->bb->index;
6020 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6022 y = pbi->reg_next_use[regno_first];
6024 /* The next use is no longer next, since a store intervenes. */
6025 for (i = regno_first; i <= regno_last; ++i)
6026 pbi->reg_next_use[i] = 0;
6029 if (flags & PROP_REG_INFO)
6031 for (i = regno_first; i <= regno_last; ++i)
6033 /* Count (weighted) references, stores, etc. This counts a
6034 register twice if it is modified, but that is correct. */
6035 REG_N_SETS (i) += 1;
6036 REG_N_REFS (i) += 1;
6037 REG_FREQ (i) += (optimize_size || !pbi->bb->frequency
6038 ? 1 : pbi->bb->frequency);
6040 /* The insns where a reg is live are normally counted
6041 elsewhere, but we want the count to include the insn
6042 where the reg is set, and the normal counting mechanism
6043 would not count it. */
6044 REG_LIVE_LENGTH (i) += 1;
6047 /* If this is a hard reg, record this function uses the reg. */
6048 if (regno_first < FIRST_PSEUDO_REGISTER)
6050 for (i = regno_first; i <= regno_last; i++)
6051 regs_ever_live[i] = 1;
6055 /* Keep track of which basic blocks each reg appears in. */
6056 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6057 REG_BASIC_BLOCK (regno_first) = blocknum;
6058 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6059 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6063 if (! some_was_dead)
6065 if (flags & PROP_LOG_LINKS)
6067 /* Make a logical link from the next following insn
6068 that uses this register, back to this insn.
6069 The following insns have already been processed.
6071 We don't build a LOG_LINK for hard registers containing
6072 in ASM_OPERANDs. If these registers get replaced,
6073 we might wind up changing the semantics of the insn,
6074 even if reload can make what appear to be valid
6075 assignments later. */
6076 if (y && (BLOCK_NUM (y) == blocknum)
6077 && (regno_first >= FIRST_PSEUDO_REGISTER
6078 || asm_noperands (PATTERN (y)) < 0))
6079 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
6084 else if (! some_was_live)
6086 if (flags & PROP_REG_INFO)
6087 REG_N_DEATHS (regno_first) += 1;
6089 if (flags & PROP_DEATH_NOTES)
6091 /* Note that dead stores have already been deleted
6092 when possible. If we get here, we have found a
6093 dead store that cannot be eliminated (because the
6094 same insn does something useful). Indicate this
6095 by marking the reg being set as dying here. */
6097 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6102 if (flags & PROP_DEATH_NOTES)
6104 /* This is a case where we have a multi-word hard register
6105 and some, but not all, of the words of the register are
6106 needed in subsequent insns. Write REG_UNUSED notes
6107 for those parts that were not needed. This case should
6110 for (i = regno_first; i <= regno_last; ++i)
6111 if (! REGNO_REG_SET_P (pbi->reg_live, i))
6113 = alloc_EXPR_LIST (REG_UNUSED,
6114 gen_rtx_REG (reg_raw_mode[i], i),
6120 /* Mark the register as being dead. */
6122 /* The stack pointer is never dead. Well, not strictly true,
6123 but it's very difficult to tell from here. Hopefully
6124 combine_stack_adjustments will fix up the most egregious
6126 && regno_first != STACK_POINTER_REGNUM)
6128 for (i = regno_first; i <= regno_last; ++i)
6129 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
6130 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
6133 else if (GET_CODE (reg) == REG)
6135 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6136 pbi->reg_next_use[regno_first] = 0;
6139 /* If this is the last pass and this is a SCRATCH, show it will be dying
6140 here and count it. */
6141 else if (GET_CODE (reg) == SCRATCH)
6143 if (flags & PROP_DEATH_NOTES)
6145 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6149 #ifdef HAVE_conditional_execution
6150 /* Mark REGNO conditionally dead.
6151 Return true if the register is now unconditionally dead. */
6154 mark_regno_cond_dead (pbi, regno, cond)
6155 struct propagate_block_info *pbi;
6159 /* If this is a store to a predicate register, the value of the
6160 predicate is changing, we don't know that the predicate as seen
6161 before is the same as that seen after. Flush all dependent
6162 conditions from reg_cond_dead. This will make all such
6163 conditionally live registers unconditionally live. */
6164 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
6165 flush_reg_cond_reg (pbi, regno);
6167 /* If this is an unconditional store, remove any conditional
6168 life that may have existed. */
6169 if (cond == NULL_RTX)
6170 splay_tree_remove (pbi->reg_cond_dead, regno);
6173 splay_tree_node node;
6174 struct reg_cond_life_info *rcli;
6177 /* Otherwise this is a conditional set. Record that fact.
6178 It may have been conditionally used, or there may be a
6179 subsequent set with a complimentary condition. */
6181 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
6184 /* The register was unconditionally live previously.
6185 Record the current condition as the condition under
6186 which it is dead. */
6187 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6188 rcli->condition = cond;
6189 rcli->stores = cond;
6190 rcli->orig_condition = const0_rtx;
6191 splay_tree_insert (pbi->reg_cond_dead, regno,
6192 (splay_tree_value) rcli);
6194 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6196 /* Not unconditionaly dead. */
6201 /* The register was conditionally live previously.
6202 Add the new condition to the old. */
6203 rcli = (struct reg_cond_life_info *) node->value;
6204 ncond = rcli->condition;
6205 ncond = ior_reg_cond (ncond, cond, 1);
6206 if (rcli->stores == const0_rtx)
6207 rcli->stores = cond;
6208 else if (rcli->stores != const1_rtx)
6209 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
6211 /* If the register is now unconditionally dead, remove the entry
6212 in the splay_tree. A register is unconditionally dead if the
6213 dead condition ncond is true. A register is also unconditionally
6214 dead if the sum of all conditional stores is an unconditional
6215 store (stores is true), and the dead condition is identically the
6216 same as the original dead condition initialized at the end of
6217 the block. This is a pointer compare, not an rtx_equal_p
6219 if (ncond == const1_rtx
6220 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
6221 splay_tree_remove (pbi->reg_cond_dead, regno);
6224 rcli->condition = ncond;
6226 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6228 /* Not unconditionaly dead. */
6237 /* Called from splay_tree_delete for pbi->reg_cond_life. */
6240 free_reg_cond_life_info (value)
6241 splay_tree_value value;
6243 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
6247 /* Helper function for flush_reg_cond_reg. */
6250 flush_reg_cond_reg_1 (node, data)
6251 splay_tree_node node;
6254 struct reg_cond_life_info *rcli;
6255 int *xdata = (int *) data;
6256 unsigned int regno = xdata[0];
6258 /* Don't need to search if last flushed value was farther on in
6259 the in-order traversal. */
6260 if (xdata[1] >= (int) node->key)
6263 /* Splice out portions of the expression that refer to regno. */
6264 rcli = (struct reg_cond_life_info *) node->value;
6265 rcli->condition = elim_reg_cond (rcli->condition, regno);
6266 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
6267 rcli->stores = elim_reg_cond (rcli->stores, regno);
6269 /* If the entire condition is now false, signal the node to be removed. */
6270 if (rcli->condition == const0_rtx)
6272 xdata[1] = node->key;
6275 else if (rcli->condition == const1_rtx)
6281 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
6284 flush_reg_cond_reg (pbi, regno)
6285 struct propagate_block_info *pbi;
6292 while (splay_tree_foreach (pbi->reg_cond_dead,
6293 flush_reg_cond_reg_1, pair) == -1)
6294 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
6296 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
6299 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
6300 For ior/and, the ADD flag determines whether we want to add the new
6301 condition X to the old one unconditionally. If it is zero, we will
6302 only return a new expression if X allows us to simplify part of
6303 OLD, otherwise we return OLD unchanged to the caller.
6304 If ADD is nonzero, we will return a new condition in all cases. The
6305 toplevel caller of one of these functions should always pass 1 for
6309 ior_reg_cond (old, x, add)
6315 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6317 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6318 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
6319 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6321 if (GET_CODE (x) == GET_CODE (old)
6322 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6326 return gen_rtx_IOR (0, old, x);
6329 switch (GET_CODE (old))
6332 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6333 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6334 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6336 if (op0 == const0_rtx)
6338 if (op1 == const0_rtx)
6340 if (op0 == const1_rtx || op1 == const1_rtx)
6342 if (op0 == XEXP (old, 0))
6343 op0 = gen_rtx_IOR (0, op0, x);
6345 op1 = gen_rtx_IOR (0, op1, x);
6346 return gen_rtx_IOR (0, op0, op1);
6350 return gen_rtx_IOR (0, old, x);
6353 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6354 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6355 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6357 if (op0 == const1_rtx)
6359 if (op1 == const1_rtx)
6361 if (op0 == const0_rtx || op1 == const0_rtx)
6363 if (op0 == XEXP (old, 0))
6364 op0 = gen_rtx_IOR (0, op0, x);
6366 op1 = gen_rtx_IOR (0, op1, x);
6367 return gen_rtx_AND (0, op0, op1);
6371 return gen_rtx_IOR (0, old, x);
6374 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6375 if (op0 != XEXP (old, 0))
6376 return not_reg_cond (op0);
6379 return gen_rtx_IOR (0, old, x);
6390 enum rtx_code x_code;
6392 if (x == const0_rtx)
6394 else if (x == const1_rtx)
6396 x_code = GET_CODE (x);
6399 if (GET_RTX_CLASS (x_code) == '<'
6400 && GET_CODE (XEXP (x, 0)) == REG)
6402 if (XEXP (x, 1) != const0_rtx)
6405 return gen_rtx_fmt_ee (reverse_condition (x_code),
6406 VOIDmode, XEXP (x, 0), const0_rtx);
6408 return gen_rtx_NOT (0, x);
6412 and_reg_cond (old, x, add)
6418 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6420 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6421 && GET_CODE (x) == reverse_condition (GET_CODE (old))
6422 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6424 if (GET_CODE (x) == GET_CODE (old)
6425 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6429 return gen_rtx_AND (0, old, x);
6432 switch (GET_CODE (old))
6435 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6436 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6437 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6439 if (op0 == const0_rtx)
6441 if (op1 == const0_rtx)
6443 if (op0 == const1_rtx || op1 == const1_rtx)
6445 if (op0 == XEXP (old, 0))
6446 op0 = gen_rtx_AND (0, op0, x);
6448 op1 = gen_rtx_AND (0, op1, x);
6449 return gen_rtx_IOR (0, op0, op1);
6453 return gen_rtx_AND (0, old, x);
6456 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6457 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6458 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6460 if (op0 == const1_rtx)
6462 if (op1 == const1_rtx)
6464 if (op0 == const0_rtx || op1 == const0_rtx)
6466 if (op0 == XEXP (old, 0))
6467 op0 = gen_rtx_AND (0, op0, x);
6469 op1 = gen_rtx_AND (0, op1, x);
6470 return gen_rtx_AND (0, op0, op1);
6475 /* If X is identical to one of the existing terms of the AND,
6476 then just return what we already have. */
6477 /* ??? There really should be some sort of recursive check here in
6478 case there are nested ANDs. */
6479 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
6480 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
6481 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
6482 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
6485 return gen_rtx_AND (0, old, x);
6488 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6489 if (op0 != XEXP (old, 0))
6490 return not_reg_cond (op0);
6493 return gen_rtx_AND (0, old, x);
6500 /* Given a condition X, remove references to reg REGNO and return the
6501 new condition. The removal will be done so that all conditions
6502 involving REGNO are considered to evaluate to false. This function
6503 is used when the value of REGNO changes. */
6506 elim_reg_cond (x, regno)
6512 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
6514 if (REGNO (XEXP (x, 0)) == regno)
6519 switch (GET_CODE (x))
6522 op0 = elim_reg_cond (XEXP (x, 0), regno);
6523 op1 = elim_reg_cond (XEXP (x, 1), regno);
6524 if (op0 == const0_rtx || op1 == const0_rtx)
6526 if (op0 == const1_rtx)
6528 if (op1 == const1_rtx)
6530 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6532 return gen_rtx_AND (0, op0, op1);
6535 op0 = elim_reg_cond (XEXP (x, 0), regno);
6536 op1 = elim_reg_cond (XEXP (x, 1), regno);
6537 if (op0 == const1_rtx || op1 == const1_rtx)
6539 if (op0 == const0_rtx)
6541 if (op1 == const0_rtx)
6543 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6545 return gen_rtx_IOR (0, op0, op1);
6548 op0 = elim_reg_cond (XEXP (x, 0), regno);
6549 if (op0 == const0_rtx)
6551 if (op0 == const1_rtx)
6553 if (op0 != XEXP (x, 0))
6554 return not_reg_cond (op0);
6561 #endif /* HAVE_conditional_execution */
6565 /* Try to substitute the auto-inc expression INC as the address inside
6566 MEM which occurs in INSN. Currently, the address of MEM is an expression
6567 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
6568 that has a single set whose source is a PLUS of INCR_REG and something
6572 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
6573 struct propagate_block_info *pbi;
6574 rtx inc, insn, mem, incr, incr_reg;
6576 int regno = REGNO (incr_reg);
6577 rtx set = single_set (incr);
6578 rtx q = SET_DEST (set);
6579 rtx y = SET_SRC (set);
6580 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
6582 /* Make sure this reg appears only once in this insn. */
6583 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
6586 if (dead_or_set_p (incr, incr_reg)
6587 /* Mustn't autoinc an eliminable register. */
6588 && (regno >= FIRST_PSEUDO_REGISTER
6589 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
6591 /* This is the simple case. Try to make the auto-inc. If
6592 we can't, we are done. Otherwise, we will do any
6593 needed updates below. */
6594 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
6597 else if (GET_CODE (q) == REG
6598 /* PREV_INSN used here to check the semi-open interval
6600 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
6601 /* We must also check for sets of q as q may be
6602 a call clobbered hard register and there may
6603 be a call between PREV_INSN (insn) and incr. */
6604 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
6606 /* We have *p followed sometime later by q = p+size.
6607 Both p and q must be live afterward,
6608 and q is not used between INSN and its assignment.
6609 Change it to q = p, ...*q..., q = q+size.
6610 Then fall into the usual case. */
6614 emit_move_insn (q, incr_reg);
6615 insns = get_insns ();
6618 if (basic_block_for_insn)
6619 for (temp = insns; temp; temp = NEXT_INSN (temp))
6620 set_block_for_insn (temp, pbi->bb);
6622 /* If we can't make the auto-inc, or can't make the
6623 replacement into Y, exit. There's no point in making
6624 the change below if we can't do the auto-inc and doing
6625 so is not correct in the pre-inc case. */
6628 validate_change (insn, &XEXP (mem, 0), inc, 1);
6629 validate_change (incr, &XEXP (y, opnum), q, 1);
6630 if (! apply_change_group ())
6633 /* We now know we'll be doing this change, so emit the
6634 new insn(s) and do the updates. */
6635 emit_insns_before (insns, insn);
6637 if (pbi->bb->head == insn)
6638 pbi->bb->head = insns;
6640 /* INCR will become a NOTE and INSN won't contain a
6641 use of INCR_REG. If a use of INCR_REG was just placed in
6642 the insn before INSN, make that the next use.
6643 Otherwise, invalidate it. */
6644 if (GET_CODE (PREV_INSN (insn)) == INSN
6645 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
6646 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
6647 pbi->reg_next_use[regno] = PREV_INSN (insn);
6649 pbi->reg_next_use[regno] = 0;
6654 /* REGNO is now used in INCR which is below INSN, but
6655 it previously wasn't live here. If we don't mark
6656 it as live, we'll put a REG_DEAD note for it
6657 on this insn, which is incorrect. */
6658 SET_REGNO_REG_SET (pbi->reg_live, regno);
6660 /* If there are any calls between INSN and INCR, show
6661 that REGNO now crosses them. */
6662 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
6663 if (GET_CODE (temp) == CALL_INSN)
6664 REG_N_CALLS_CROSSED (regno)++;
6669 /* If we haven't returned, it means we were able to make the
6670 auto-inc, so update the status. First, record that this insn
6671 has an implicit side effect. */
6673 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
6675 /* Modify the old increment-insn to simply copy
6676 the already-incremented value of our register. */
6677 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
6680 /* If that makes it a no-op (copying the register into itself) delete
6681 it so it won't appear to be a "use" and a "set" of this
6683 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
6685 /* If the original source was dead, it's dead now. */
6688 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
6690 remove_note (incr, note);
6691 if (XEXP (note, 0) != incr_reg)
6692 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
6695 PUT_CODE (incr, NOTE);
6696 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
6697 NOTE_SOURCE_FILE (incr) = 0;
6700 if (regno >= FIRST_PSEUDO_REGISTER)
6702 /* Count an extra reference to the reg. When a reg is
6703 incremented, spilling it is worse, so we want to make
6704 that less likely. */
6705 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
6706 ? 1 : pbi->bb->frequency);
6708 /* Count the increment as a setting of the register,
6709 even though it isn't a SET in rtl. */
6710 REG_N_SETS (regno)++;
6714 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
6718 find_auto_inc (pbi, x, insn)
6719 struct propagate_block_info *pbi;
6723 rtx addr = XEXP (x, 0);
6724 HOST_WIDE_INT offset = 0;
6725 rtx set, y, incr, inc_val;
6727 int size = GET_MODE_SIZE (GET_MODE (x));
6729 if (GET_CODE (insn) == JUMP_INSN)
6732 /* Here we detect use of an index register which might be good for
6733 postincrement, postdecrement, preincrement, or predecrement. */
6735 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
6736 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
6738 if (GET_CODE (addr) != REG)
6741 regno = REGNO (addr);
6743 /* Is the next use an increment that might make auto-increment? */
6744 incr = pbi->reg_next_use[regno];
6745 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
6747 set = single_set (incr);
6748 if (set == 0 || GET_CODE (set) != SET)
6752 if (GET_CODE (y) != PLUS)
6755 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
6756 inc_val = XEXP (y, 1);
6757 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
6758 inc_val = XEXP (y, 0);
6762 if (GET_CODE (inc_val) == CONST_INT)
6764 if (HAVE_POST_INCREMENT
6765 && (INTVAL (inc_val) == size && offset == 0))
6766 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
6768 else if (HAVE_POST_DECREMENT
6769 && (INTVAL (inc_val) == -size && offset == 0))
6770 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
6772 else if (HAVE_PRE_INCREMENT
6773 && (INTVAL (inc_val) == size && offset == size))
6774 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
6776 else if (HAVE_PRE_DECREMENT
6777 && (INTVAL (inc_val) == -size && offset == -size))
6778 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
6780 else if (HAVE_POST_MODIFY_DISP && offset == 0)
6781 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6782 gen_rtx_PLUS (Pmode,
6785 insn, x, incr, addr);
6787 else if (GET_CODE (inc_val) == REG
6788 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
6792 if (HAVE_POST_MODIFY_REG && offset == 0)
6793 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6794 gen_rtx_PLUS (Pmode,
6797 insn, x, incr, addr);
6801 #endif /* AUTO_INC_DEC */
6804 mark_used_reg (pbi, reg, cond, insn)
6805 struct propagate_block_info *pbi;
6807 rtx cond ATTRIBUTE_UNUSED;
6810 unsigned int regno_first, regno_last, i;
6811 int some_was_live, some_was_dead, some_not_set;
6813 regno_last = regno_first = REGNO (reg);
6814 if (regno_first < FIRST_PSEUDO_REGISTER)
6815 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
6817 /* Find out if any of this register is live after this instruction. */
6818 some_was_live = some_was_dead = 0;
6819 for (i = regno_first; i <= regno_last; ++i)
6821 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
6822 some_was_live |= needed_regno;
6823 some_was_dead |= ! needed_regno;
6826 /* Find out if any of the register was set this insn. */
6828 for (i = regno_first; i <= regno_last; ++i)
6829 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
6831 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6833 /* Record where each reg is used, so when the reg is set we know
6834 the next insn that uses it. */
6835 pbi->reg_next_use[regno_first] = insn;
6838 if (pbi->flags & PROP_REG_INFO)
6840 if (regno_first < FIRST_PSEUDO_REGISTER)
6842 /* If this is a register we are going to try to eliminate,
6843 don't mark it live here. If we are successful in
6844 eliminating it, it need not be live unless it is used for
6845 pseudos, in which case it will have been set live when it
6846 was allocated to the pseudos. If the register will not
6847 be eliminated, reload will set it live at that point.
6849 Otherwise, record that this function uses this register. */
6850 /* ??? The PPC backend tries to "eliminate" on the pic
6851 register to itself. This should be fixed. In the mean
6852 time, hack around it. */
6854 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
6855 && (regno_first == FRAME_POINTER_REGNUM
6856 || regno_first == ARG_POINTER_REGNUM)))
6857 for (i = regno_first; i <= regno_last; ++i)
6858 regs_ever_live[i] = 1;
6862 /* Keep track of which basic block each reg appears in. */
6864 register int blocknum = pbi->bb->index;
6865 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6866 REG_BASIC_BLOCK (regno_first) = blocknum;
6867 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6868 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6870 /* Count (weighted) number of uses of each reg. */
6871 REG_FREQ (regno_first)
6872 += (optimize_size || !pbi->bb->frequency ? 1 : pbi->bb->frequency);
6873 REG_N_REFS (regno_first)++;
6877 /* Record and count the insns in which a reg dies. If it is used in
6878 this insn and was dead below the insn then it dies in this insn.
6879 If it was set in this insn, we do not make a REG_DEAD note;
6880 likewise if we already made such a note. */
6881 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
6885 /* Check for the case where the register dying partially
6886 overlaps the register set by this insn. */
6887 if (regno_first != regno_last)
6888 for (i = regno_first; i <= regno_last; ++i)
6889 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
6891 /* If none of the words in X is needed, make a REG_DEAD note.
6892 Otherwise, we must make partial REG_DEAD notes. */
6893 if (! some_was_live)
6895 if ((pbi->flags & PROP_DEATH_NOTES)
6896 && ! find_regno_note (insn, REG_DEAD, regno_first))
6898 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
6900 if (pbi->flags & PROP_REG_INFO)
6901 REG_N_DEATHS (regno_first)++;
6905 /* Don't make a REG_DEAD note for a part of a register
6906 that is set in the insn. */
6907 for (i = regno_first; i <= regno_last; ++i)
6908 if (! REGNO_REG_SET_P (pbi->reg_live, i)
6909 && ! dead_or_set_regno_p (insn, i))
6911 = alloc_EXPR_LIST (REG_DEAD,
6912 gen_rtx_REG (reg_raw_mode[i], i),
6917 /* Mark the register as being live. */
6918 for (i = regno_first; i <= regno_last; ++i)
6920 SET_REGNO_REG_SET (pbi->reg_live, i);
6922 #ifdef HAVE_conditional_execution
6923 /* If this is a conditional use, record that fact. If it is later
6924 conditionally set, we'll know to kill the register. */
6925 if (cond != NULL_RTX)
6927 splay_tree_node node;
6928 struct reg_cond_life_info *rcli;
6933 node = splay_tree_lookup (pbi->reg_cond_dead, i);
6936 /* The register was unconditionally live previously.
6937 No need to do anything. */
6941 /* The register was conditionally live previously.
6942 Subtract the new life cond from the old death cond. */
6943 rcli = (struct reg_cond_life_info *) node->value;
6944 ncond = rcli->condition;
6945 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
6947 /* If the register is now unconditionally live,
6948 remove the entry in the splay_tree. */
6949 if (ncond == const0_rtx)
6950 splay_tree_remove (pbi->reg_cond_dead, i);
6953 rcli->condition = ncond;
6954 SET_REGNO_REG_SET (pbi->reg_cond_reg,
6955 REGNO (XEXP (cond, 0)));
6961 /* The register was not previously live at all. Record
6962 the condition under which it is still dead. */
6963 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6964 rcli->condition = not_reg_cond (cond);
6965 rcli->stores = const0_rtx;
6966 rcli->orig_condition = const0_rtx;
6967 splay_tree_insert (pbi->reg_cond_dead, i,
6968 (splay_tree_value) rcli);
6970 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6973 else if (some_was_live)
6975 /* The register may have been conditionally live previously, but
6976 is now unconditionally live. Remove it from the conditionally
6977 dead list, so that a conditional set won't cause us to think
6979 splay_tree_remove (pbi->reg_cond_dead, i);
6985 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
6986 This is done assuming the registers needed from X are those that
6987 have 1-bits in PBI->REG_LIVE.
6989 INSN is the containing instruction. If INSN is dead, this function
6993 mark_used_regs (pbi, x, cond, insn)
6994 struct propagate_block_info *pbi;
6997 register RTX_CODE code;
6999 int flags = pbi->flags;
7002 code = GET_CODE (x);
7022 /* If we are clobbering a MEM, mark any registers inside the address
7024 if (GET_CODE (XEXP (x, 0)) == MEM)
7025 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
7029 /* Don't bother watching stores to mems if this is not the
7030 final pass. We'll not be deleting dead stores this round. */
7031 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
7033 /* Invalidate the data for the last MEM stored, but only if MEM is
7034 something that can be stored into. */
7035 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
7036 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
7037 /* Needn't clear the memory set list. */
7041 rtx temp = pbi->mem_set_list;
7042 rtx prev = NULL_RTX;
7047 next = XEXP (temp, 1);
7048 if (anti_dependence (XEXP (temp, 0), x))
7050 /* Splice temp out of the list. */
7052 XEXP (prev, 1) = next;
7054 pbi->mem_set_list = next;
7055 free_EXPR_LIST_node (temp);
7056 pbi->mem_set_list_len--;
7064 /* If the memory reference had embedded side effects (autoincrement
7065 address modes. Then we may need to kill some entries on the
7068 invalidate_mems_from_autoinc (pbi, insn);
7072 if (flags & PROP_AUTOINC)
7073 find_auto_inc (pbi, x, insn);
7078 #ifdef CLASS_CANNOT_CHANGE_MODE
7079 if (GET_CODE (SUBREG_REG (x)) == REG
7080 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
7081 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
7082 GET_MODE (SUBREG_REG (x))))
7083 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
7086 /* While we're here, optimize this case. */
7088 if (GET_CODE (x) != REG)
7093 /* See a register other than being set => mark it as needed. */
7094 mark_used_reg (pbi, x, cond, insn);
7099 register rtx testreg = SET_DEST (x);
7102 /* If storing into MEM, don't show it as being used. But do
7103 show the address as being used. */
7104 if (GET_CODE (testreg) == MEM)
7107 if (flags & PROP_AUTOINC)
7108 find_auto_inc (pbi, testreg, insn);
7110 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
7111 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7115 /* Storing in STRICT_LOW_PART is like storing in a reg
7116 in that this SET might be dead, so ignore it in TESTREG.
7117 but in some other ways it is like using the reg.
7119 Storing in a SUBREG or a bit field is like storing the entire
7120 register in that if the register's value is not used
7121 then this SET is not needed. */
7122 while (GET_CODE (testreg) == STRICT_LOW_PART
7123 || GET_CODE (testreg) == ZERO_EXTRACT
7124 || GET_CODE (testreg) == SIGN_EXTRACT
7125 || GET_CODE (testreg) == SUBREG)
7127 #ifdef CLASS_CANNOT_CHANGE_MODE
7128 if (GET_CODE (testreg) == SUBREG
7129 && GET_CODE (SUBREG_REG (testreg)) == REG
7130 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
7131 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
7132 GET_MODE (testreg)))
7133 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
7136 /* Modifying a single register in an alternate mode
7137 does not use any of the old value. But these other
7138 ways of storing in a register do use the old value. */
7139 if (GET_CODE (testreg) == SUBREG
7140 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
7145 testreg = XEXP (testreg, 0);
7148 /* If this is a store into a register or group of registers,
7149 recursively scan the value being stored. */
7151 if ((GET_CODE (testreg) == PARALLEL
7152 && GET_MODE (testreg) == BLKmode)
7153 || (GET_CODE (testreg) == REG
7154 && (regno = REGNO (testreg),
7155 ! (regno == FRAME_POINTER_REGNUM
7156 && (! reload_completed || frame_pointer_needed)))
7157 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
7158 && ! (regno == HARD_FRAME_POINTER_REGNUM
7159 && (! reload_completed || frame_pointer_needed))
7161 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
7162 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
7167 mark_used_regs (pbi, SET_DEST (x), cond, insn);
7168 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7175 case UNSPEC_VOLATILE:
7179 /* Traditional and volatile asm instructions must be considered to use
7180 and clobber all hard registers, all pseudo-registers and all of
7181 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
7183 Consider for instance a volatile asm that changes the fpu rounding
7184 mode. An insn should not be moved across this even if it only uses
7185 pseudo-regs because it might give an incorrectly rounded result.
7187 ?!? Unfortunately, marking all hard registers as live causes massive
7188 problems for the register allocator and marking all pseudos as live
7189 creates mountains of uninitialized variable warnings.
7191 So for now, just clear the memory set list and mark any regs
7192 we can find in ASM_OPERANDS as used. */
7193 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
7195 free_EXPR_LIST_list (&pbi->mem_set_list);
7196 pbi->mem_set_list_len = 0;
7199 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
7200 We can not just fall through here since then we would be confused
7201 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
7202 traditional asms unlike their normal usage. */
7203 if (code == ASM_OPERANDS)
7207 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
7208 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
7214 if (cond != NULL_RTX)
7217 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
7219 cond = COND_EXEC_TEST (x);
7220 x = COND_EXEC_CODE (x);
7224 /* We _do_not_ want to scan operands of phi nodes. Operands of
7225 a phi function are evaluated only when control reaches this
7226 block along a particular edge. Therefore, regs that appear
7227 as arguments to phi should not be added to the global live at
7235 /* Recursively scan the operands of this expression. */
7238 register const char *fmt = GET_RTX_FORMAT (code);
7241 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7245 /* Tail recursive case: save a function call level. */
7251 mark_used_regs (pbi, XEXP (x, i), cond, insn);
7253 else if (fmt[i] == 'E')
7256 for (j = 0; j < XVECLEN (x, i); j++)
7257 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
7266 try_pre_increment_1 (pbi, insn)
7267 struct propagate_block_info *pbi;
7270 /* Find the next use of this reg. If in same basic block,
7271 make it do pre-increment or pre-decrement if appropriate. */
7272 rtx x = single_set (insn);
7273 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
7274 * INTVAL (XEXP (SET_SRC (x), 1)));
7275 int regno = REGNO (SET_DEST (x));
7276 rtx y = pbi->reg_next_use[regno];
7278 && SET_DEST (x) != stack_pointer_rtx
7279 && BLOCK_NUM (y) == BLOCK_NUM (insn)
7280 /* Don't do this if the reg dies, or gets set in y; a standard addressing
7281 mode would be better. */
7282 && ! dead_or_set_p (y, SET_DEST (x))
7283 && try_pre_increment (y, SET_DEST (x), amount))
7285 /* We have found a suitable auto-increment and already changed
7286 insn Y to do it. So flush this increment instruction. */
7287 propagate_block_delete_insn (pbi->bb, insn);
7289 /* Count a reference to this reg for the increment insn we are
7290 deleting. When a reg is incremented, spilling it is worse,
7291 so we want to make that less likely. */
7292 if (regno >= FIRST_PSEUDO_REGISTER)
7294 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
7295 ? 1 : pbi->bb->frequency);
7296 REG_N_SETS (regno)++;
7299 /* Flush any remembered memories depending on the value of
7300 the incremented register. */
7301 invalidate_mems_from_set (pbi, SET_DEST (x));
7308 /* Try to change INSN so that it does pre-increment or pre-decrement
7309 addressing on register REG in order to add AMOUNT to REG.
7310 AMOUNT is negative for pre-decrement.
7311 Returns 1 if the change could be made.
7312 This checks all about the validity of the result of modifying INSN. */
7315 try_pre_increment (insn, reg, amount)
7317 HOST_WIDE_INT amount;
7321 /* Nonzero if we can try to make a pre-increment or pre-decrement.
7322 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
7324 /* Nonzero if we can try to make a post-increment or post-decrement.
7325 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
7326 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
7327 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
7330 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
7333 /* From the sign of increment, see which possibilities are conceivable
7334 on this target machine. */
7335 if (HAVE_PRE_INCREMENT && amount > 0)
7337 if (HAVE_POST_INCREMENT && amount > 0)
7340 if (HAVE_PRE_DECREMENT && amount < 0)
7342 if (HAVE_POST_DECREMENT && amount < 0)
7345 if (! (pre_ok || post_ok))
7348 /* It is not safe to add a side effect to a jump insn
7349 because if the incremented register is spilled and must be reloaded
7350 there would be no way to store the incremented value back in memory. */
7352 if (GET_CODE (insn) == JUMP_INSN)
7357 use = find_use_as_address (PATTERN (insn), reg, 0);
7358 if (post_ok && (use == 0 || use == (rtx) 1))
7360 use = find_use_as_address (PATTERN (insn), reg, -amount);
7364 if (use == 0 || use == (rtx) 1)
7367 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
7370 /* See if this combination of instruction and addressing mode exists. */
7371 if (! validate_change (insn, &XEXP (use, 0),
7372 gen_rtx_fmt_e (amount > 0
7373 ? (do_post ? POST_INC : PRE_INC)
7374 : (do_post ? POST_DEC : PRE_DEC),
7378 /* Record that this insn now has an implicit side effect on X. */
7379 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
7383 #endif /* AUTO_INC_DEC */
7385 /* Find the place in the rtx X where REG is used as a memory address.
7386 Return the MEM rtx that so uses it.
7387 If PLUSCONST is nonzero, search instead for a memory address equivalent to
7388 (plus REG (const_int PLUSCONST)).
7390 If such an address does not appear, return 0.
7391 If REG appears more than once, or is used other than in such an address,
7395 find_use_as_address (x, reg, plusconst)
7398 HOST_WIDE_INT plusconst;
7400 enum rtx_code code = GET_CODE (x);
7401 const char *fmt = GET_RTX_FORMAT (code);
7403 register rtx value = 0;
7406 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
7409 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
7410 && XEXP (XEXP (x, 0), 0) == reg
7411 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
7412 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
7415 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
7417 /* If REG occurs inside a MEM used in a bit-field reference,
7418 that is unacceptable. */
7419 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
7420 return (rtx) (HOST_WIDE_INT) 1;
7424 return (rtx) (HOST_WIDE_INT) 1;
7426 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7430 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
7434 return (rtx) (HOST_WIDE_INT) 1;
7436 else if (fmt[i] == 'E')
7439 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7441 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
7445 return (rtx) (HOST_WIDE_INT) 1;
7453 /* Write information about registers and basic blocks into FILE.
7454 This is part of making a debugging dump. */
7457 dump_regset (r, outf)
7464 fputs (" (nil)", outf);
7468 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
7470 fprintf (outf, " %d", i);
7471 if (i < FIRST_PSEUDO_REGISTER)
7472 fprintf (outf, " [%s]",
7477 /* Print a human-reaable representation of R on the standard error
7478 stream. This function is designed to be used from within the
7485 dump_regset (r, stderr);
7486 putc ('\n', stderr);
7490 dump_flow_info (file)
7494 static const char * const reg_class_names[] = REG_CLASS_NAMES;
7496 fprintf (file, "%d registers.\n", max_regno);
7497 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
7500 enum reg_class class, altclass;
7501 fprintf (file, "\nRegister %d used %d times across %d insns",
7502 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
7503 if (REG_BASIC_BLOCK (i) >= 0)
7504 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
7506 fprintf (file, "; set %d time%s", REG_N_SETS (i),
7507 (REG_N_SETS (i) == 1) ? "" : "s");
7508 if (REG_USERVAR_P (regno_reg_rtx[i]))
7509 fprintf (file, "; user var");
7510 if (REG_N_DEATHS (i) != 1)
7511 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
7512 if (REG_N_CALLS_CROSSED (i) == 1)
7513 fprintf (file, "; crosses 1 call");
7514 else if (REG_N_CALLS_CROSSED (i))
7515 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
7516 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
7517 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
7518 class = reg_preferred_class (i);
7519 altclass = reg_alternate_class (i);
7520 if (class != GENERAL_REGS || altclass != ALL_REGS)
7522 if (altclass == ALL_REGS || class == ALL_REGS)
7523 fprintf (file, "; pref %s", reg_class_names[(int) class]);
7524 else if (altclass == NO_REGS)
7525 fprintf (file, "; %s or none", reg_class_names[(int) class]);
7527 fprintf (file, "; pref %s, else %s",
7528 reg_class_names[(int) class],
7529 reg_class_names[(int) altclass]);
7531 if (REG_POINTER (regno_reg_rtx[i]))
7532 fprintf (file, "; pointer");
7533 fprintf (file, ".\n");
7536 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
7537 for (i = 0; i < n_basic_blocks; i++)
7539 register basic_block bb = BASIC_BLOCK (i);
7542 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count ",
7543 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth);
7544 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7545 fprintf (file, ", freq %i.\n", bb->frequency);
7547 fprintf (file, "Predecessors: ");
7548 for (e = bb->pred; e; e = e->pred_next)
7549 dump_edge_info (file, e, 0);
7551 fprintf (file, "\nSuccessors: ");
7552 for (e = bb->succ; e; e = e->succ_next)
7553 dump_edge_info (file, e, 1);
7555 fprintf (file, "\nRegisters live at start:");
7556 dump_regset (bb->global_live_at_start, file);
7558 fprintf (file, "\nRegisters live at end:");
7559 dump_regset (bb->global_live_at_end, file);
7570 dump_flow_info (stderr);
7574 dump_edge_info (file, e, do_succ)
7579 basic_block side = (do_succ ? e->dest : e->src);
7581 if (side == ENTRY_BLOCK_PTR)
7582 fputs (" ENTRY", file);
7583 else if (side == EXIT_BLOCK_PTR)
7584 fputs (" EXIT", file);
7586 fprintf (file, " %d", side->index);
7589 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
7593 fprintf (file, " count:");
7594 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) e->count);
7599 static const char * const bitnames[] = {
7600 "fallthru", "crit", "ab", "abcall", "eh", "fake"
7603 int i, flags = e->flags;
7607 for (i = 0; flags; i++)
7608 if (flags & (1 << i))
7614 if (i < (int) ARRAY_SIZE (bitnames))
7615 fputs (bitnames[i], file);
7617 fprintf (file, "%d", i);
7624 /* Print out one basic block with live information at start and end. */
7635 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
7636 bb->index, bb->loop_depth);
7637 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7640 fputs (";; Predecessors: ", outf);
7641 for (e = bb->pred; e; e = e->pred_next)
7642 dump_edge_info (outf, e, 0);
7645 fputs (";; Registers live at start:", outf);
7646 dump_regset (bb->global_live_at_start, outf);
7649 for (insn = bb->head, last = NEXT_INSN (bb->end);
7651 insn = NEXT_INSN (insn))
7652 print_rtl_single (outf, insn);
7654 fputs (";; Registers live at end:", outf);
7655 dump_regset (bb->global_live_at_end, outf);
7658 fputs (";; Successors: ", outf);
7659 for (e = bb->succ; e; e = e->succ_next)
7660 dump_edge_info (outf, e, 1);
7668 dump_bb (bb, stderr);
7675 dump_bb (BASIC_BLOCK (n), stderr);
7678 /* Like print_rtl, but also print out live information for the start of each
7682 print_rtl_with_bb (outf, rtx_first)
7686 register rtx tmp_rtx;
7689 fprintf (outf, "(nil)\n");
7693 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
7694 int max_uid = get_max_uid ();
7695 basic_block *start = (basic_block *)
7696 xcalloc (max_uid, sizeof (basic_block));
7697 basic_block *end = (basic_block *)
7698 xcalloc (max_uid, sizeof (basic_block));
7699 enum bb_state *in_bb_p = (enum bb_state *)
7700 xcalloc (max_uid, sizeof (enum bb_state));
7702 for (i = n_basic_blocks - 1; i >= 0; i--)
7704 basic_block bb = BASIC_BLOCK (i);
7707 start[INSN_UID (bb->head)] = bb;
7708 end[INSN_UID (bb->end)] = bb;
7709 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
7711 enum bb_state state = IN_MULTIPLE_BB;
7712 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
7714 in_bb_p[INSN_UID (x)] = state;
7721 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
7726 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
7728 fprintf (outf, ";; Start of basic block %d, registers live:",
7730 dump_regset (bb->global_live_at_start, outf);
7734 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
7735 && GET_CODE (tmp_rtx) != NOTE
7736 && GET_CODE (tmp_rtx) != BARRIER)
7737 fprintf (outf, ";; Insn is not within a basic block\n");
7738 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
7739 fprintf (outf, ";; Insn is in multiple basic blocks\n");
7741 did_output = print_rtl_single (outf, tmp_rtx);
7743 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
7745 fprintf (outf, ";; End of basic block %d, registers live:\n",
7747 dump_regset (bb->global_live_at_end, outf);
7760 if (current_function_epilogue_delay_list != 0)
7762 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
7763 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
7764 tmp_rtx = XEXP (tmp_rtx, 1))
7765 print_rtl_single (outf, XEXP (tmp_rtx, 0));
7769 /* Dump the rtl into the current debugging dump file, then abort. */
7772 print_rtl_and_abort_fcn (file, line, function)
7775 const char *function;
7779 print_rtl_with_bb (rtl_dump_file, get_insns ());
7780 fclose (rtl_dump_file);
7783 fancy_abort (file, line, function);
7786 /* Recompute register set/reference counts immediately prior to register
7789 This avoids problems with set/reference counts changing to/from values
7790 which have special meanings to the register allocators.
7792 Additionally, the reference counts are the primary component used by the
7793 register allocators to prioritize pseudos for allocation to hard regs.
7794 More accurate reference counts generally lead to better register allocation.
7796 F is the first insn to be scanned.
7798 LOOP_STEP denotes how much loop_depth should be incremented per
7799 loop nesting level in order to increase the ref count more for
7800 references in a loop.
7802 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
7803 possibly other information which is used by the register allocators. */
7806 recompute_reg_usage (f, loop_step)
7807 rtx f ATTRIBUTE_UNUSED;
7808 int loop_step ATTRIBUTE_UNUSED;
7810 allocate_reg_life_data ();
7811 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
7814 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
7815 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
7816 of the number of registers that died. */
7819 count_or_remove_death_notes (blocks, kill)
7825 for (i = n_basic_blocks - 1; i >= 0; --i)
7830 if (blocks && ! TEST_BIT (blocks, i))
7833 bb = BASIC_BLOCK (i);
7835 for (insn = bb->head;; insn = NEXT_INSN (insn))
7839 rtx *pprev = ®_NOTES (insn);
7844 switch (REG_NOTE_KIND (link))
7847 if (GET_CODE (XEXP (link, 0)) == REG)
7849 rtx reg = XEXP (link, 0);
7852 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
7855 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
7863 rtx next = XEXP (link, 1);
7864 free_EXPR_LIST_node (link);
7865 *pprev = link = next;
7871 pprev = &XEXP (link, 1);
7878 if (insn == bb->end)
7887 /* Update insns block within BB. */
7890 update_bb_for_insn (bb)
7895 if (! basic_block_for_insn)
7898 for (insn = bb->head; ; insn = NEXT_INSN (insn))
7900 set_block_for_insn (insn, bb);
7902 if (insn == bb->end)
7908 /* Record INSN's block as BB. */
7911 set_block_for_insn (insn, bb)
7915 size_t uid = INSN_UID (insn);
7916 if (uid >= basic_block_for_insn->num_elements)
7920 /* Add one-eighth the size so we don't keep calling xrealloc. */
7921 new_size = uid + (uid + 7) / 8;
7923 VARRAY_GROW (basic_block_for_insn, new_size);
7925 VARRAY_BB (basic_block_for_insn, uid) = bb;
7928 /* When a new insn has been inserted into an existing block, it will
7929 sometimes emit more than a single insn. This routine will set the
7930 block number for the specified insn, and look backwards in the insn
7931 chain to see if there are any other uninitialized insns immediately
7932 previous to this one, and set the block number for them too. */
7935 set_block_for_new_insns (insn, bb)
7939 set_block_for_insn (insn, bb);
7941 /* Scan the previous instructions setting the block number until we find
7942 an instruction that has the block number set, or we find a note
7944 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
7946 if (GET_CODE (insn) == NOTE)
7948 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
7949 || BLOCK_FOR_INSN (insn) == 0)
7950 set_block_for_insn (insn, bb);
7956 /* Verify the CFG consistency. This function check some CFG invariants and
7957 aborts when something is wrong. Hope that this function will help to
7958 convert many optimization passes to preserve CFG consistent.
7960 Currently it does following checks:
7962 - test head/end pointers
7963 - overlapping of basic blocks
7964 - edge list corectness
7965 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
7966 - tails of basic blocks (ensure that boundary is necesary)
7967 - scans body of the basic block for JUMP_INSN, CODE_LABEL
7968 and NOTE_INSN_BASIC_BLOCK
7969 - check that all insns are in the basic blocks
7970 (except the switch handling code, barriers and notes)
7971 - check that all returns are followed by barriers
7973 In future it can be extended check a lot of other stuff as well
7974 (reachability of basic blocks, life information, etc. etc.). */
7979 const int max_uid = get_max_uid ();
7980 const rtx rtx_first = get_insns ();
7981 rtx last_head = get_last_insn ();
7982 basic_block *bb_info;
7984 int i, last_bb_num_seen, num_bb_notes, err = 0;
7986 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
7988 for (i = n_basic_blocks - 1; i >= 0; i--)
7990 basic_block bb = BASIC_BLOCK (i);
7991 rtx head = bb->head;
7994 /* Verify the end of the basic block is in the INSN chain. */
7995 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
8000 error ("End insn %d for block %d not found in the insn stream.",
8001 INSN_UID (end), bb->index);
8005 /* Work backwards from the end to the head of the basic block
8006 to verify the head is in the RTL chain. */
8007 for (; x != NULL_RTX; x = PREV_INSN (x))
8009 /* While walking over the insn chain, verify insns appear
8010 in only one basic block and initialize the BB_INFO array
8011 used by other passes. */
8012 if (bb_info[INSN_UID (x)] != NULL)
8014 error ("Insn %d is in multiple basic blocks (%d and %d)",
8015 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
8018 bb_info[INSN_UID (x)] = bb;
8025 error ("Head insn %d for block %d not found in the insn stream.",
8026 INSN_UID (head), bb->index);
8033 /* Now check the basic blocks (boundaries etc.) */
8034 for (i = n_basic_blocks - 1; i >= 0; i--)
8036 basic_block bb = BASIC_BLOCK (i);
8037 /* Check corectness of edge lists */
8043 if ((e->flags & EDGE_FALLTHRU)
8044 && e->src != ENTRY_BLOCK_PTR
8045 && e->dest != EXIT_BLOCK_PTR
8046 && (e->src->index + 1 != e->dest->index
8047 || !can_fallthru (e->src, e->dest)))
8049 error ("verify_flow_info: Incorrect fallthru edge %i->%i",
8050 e->src->index, e->dest->index);
8056 error ("verify_flow_info: Basic block %d succ edge is corrupted",
8058 fprintf (stderr, "Predecessor: ");
8059 dump_edge_info (stderr, e, 0);
8060 fprintf (stderr, "\nSuccessor: ");
8061 dump_edge_info (stderr, e, 1);
8062 fprintf (stderr, "\n");
8065 if (e->dest != EXIT_BLOCK_PTR)
8067 edge e2 = e->dest->pred;
8068 while (e2 && e2 != e)
8072 error ("Basic block %i edge lists are corrupted", bb->index);
8084 error ("Basic block %d pred edge is corrupted", bb->index);
8085 fputs ("Predecessor: ", stderr);
8086 dump_edge_info (stderr, e, 0);
8087 fputs ("\nSuccessor: ", stderr);
8088 dump_edge_info (stderr, e, 1);
8089 fputc ('\n', stderr);
8092 if (e->src != ENTRY_BLOCK_PTR)
8094 edge e2 = e->src->succ;
8095 while (e2 && e2 != e)
8099 error ("Basic block %i edge lists are corrupted", bb->index);
8106 /* OK pointers are correct. Now check the header of basic
8107 block. It ought to contain optional CODE_LABEL followed
8108 by NOTE_BASIC_BLOCK. */
8110 if (GET_CODE (x) == CODE_LABEL)
8114 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
8120 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
8122 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
8129 /* Do checks for empty blocks here */
8136 if (NOTE_INSN_BASIC_BLOCK_P (x))
8138 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
8139 INSN_UID (x), bb->index);
8146 if (GET_CODE (x) == JUMP_INSN
8147 || GET_CODE (x) == CODE_LABEL
8148 || GET_CODE (x) == BARRIER)
8150 error ("In basic block %d:", bb->index);
8151 fatal_insn ("Flow control insn inside a basic block", x);
8159 last_bb_num_seen = -1;
8164 if (NOTE_INSN_BASIC_BLOCK_P (x))
8166 basic_block bb = NOTE_BASIC_BLOCK (x);
8168 if (bb->index != last_bb_num_seen + 1)
8169 /* Basic blocks not numbered consecutively. */
8172 last_bb_num_seen = bb->index;
8175 if (!bb_info[INSN_UID (x)])
8177 switch (GET_CODE (x))
8184 /* An addr_vec is placed outside any block block. */
8186 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
8187 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
8188 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
8193 /* But in any case, non-deletable labels can appear anywhere. */
8197 fatal_insn ("Insn outside basic block", x);
8202 && GET_CODE (x) == JUMP_INSN
8203 && returnjump_p (x) && ! condjump_p (x)
8204 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
8205 fatal_insn ("Return not followed by barrier", x);
8210 if (num_bb_notes != n_basic_blocks)
8212 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
8213 num_bb_notes, n_basic_blocks);
8222 /* Functions to access an edge list with a vector representation.
8223 Enough data is kept such that given an index number, the
8224 pred and succ that edge represents can be determined, or
8225 given a pred and a succ, its index number can be returned.
8226 This allows algorithms which consume a lot of memory to
8227 represent the normally full matrix of edge (pred,succ) with a
8228 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
8229 wasted space in the client code due to sparse flow graphs. */
8231 /* This functions initializes the edge list. Basically the entire
8232 flowgraph is processed, and all edges are assigned a number,
8233 and the data structure is filled in. */
8238 struct edge_list *elist;
8244 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
8248 /* Determine the number of edges in the flow graph by counting successor
8249 edges on each basic block. */
8250 for (x = 0; x < n_basic_blocks; x++)
8252 basic_block bb = BASIC_BLOCK (x);
8254 for (e = bb->succ; e; e = e->succ_next)
8257 /* Don't forget successors of the entry block. */
8258 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8261 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
8262 elist->num_blocks = block_count;
8263 elist->num_edges = num_edges;
8264 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
8268 /* Follow successors of the entry block, and register these edges. */
8269 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8271 elist->index_to_edge[num_edges] = e;
8275 for (x = 0; x < n_basic_blocks; x++)
8277 basic_block bb = BASIC_BLOCK (x);
8279 /* Follow all successors of blocks, and register these edges. */
8280 for (e = bb->succ; e; e = e->succ_next)
8282 elist->index_to_edge[num_edges] = e;
8289 /* This function free's memory associated with an edge list. */
8292 free_edge_list (elist)
8293 struct edge_list *elist;
8297 free (elist->index_to_edge);
8302 /* This function provides debug output showing an edge list. */
8305 print_edge_list (f, elist)
8307 struct edge_list *elist;
8310 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
8311 elist->num_blocks - 2, elist->num_edges);
8313 for (x = 0; x < elist->num_edges; x++)
8315 fprintf (f, " %-4d - edge(", x);
8316 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
8317 fprintf (f, "entry,");
8319 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
8321 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
8322 fprintf (f, "exit)\n");
8324 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
8328 /* This function provides an internal consistency check of an edge list,
8329 verifying that all edges are present, and that there are no
8333 verify_edge_list (f, elist)
8335 struct edge_list *elist;
8337 int x, pred, succ, index;
8340 for (x = 0; x < n_basic_blocks; x++)
8342 basic_block bb = BASIC_BLOCK (x);
8344 for (e = bb->succ; e; e = e->succ_next)
8346 pred = e->src->index;
8347 succ = e->dest->index;
8348 index = EDGE_INDEX (elist, e->src, e->dest);
8349 if (index == EDGE_INDEX_NO_EDGE)
8351 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8354 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8355 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8356 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8357 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8358 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8359 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8362 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8364 pred = e->src->index;
8365 succ = e->dest->index;
8366 index = EDGE_INDEX (elist, e->src, e->dest);
8367 if (index == EDGE_INDEX_NO_EDGE)
8369 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8372 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8373 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8374 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8375 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8376 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8377 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8379 /* We've verified that all the edges are in the list, no lets make sure
8380 there are no spurious edges in the list. */
8382 for (pred = 0; pred < n_basic_blocks; pred++)
8383 for (succ = 0; succ < n_basic_blocks; succ++)
8385 basic_block p = BASIC_BLOCK (pred);
8386 basic_block s = BASIC_BLOCK (succ);
8390 for (e = p->succ; e; e = e->succ_next)
8396 for (e = s->pred; e; e = e->pred_next)
8402 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8403 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8404 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
8406 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8407 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8408 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
8409 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8410 BASIC_BLOCK (succ)));
8412 for (succ = 0; succ < n_basic_blocks; succ++)
8414 basic_block p = ENTRY_BLOCK_PTR;
8415 basic_block s = BASIC_BLOCK (succ);
8419 for (e = p->succ; e; e = e->succ_next)
8425 for (e = s->pred; e; e = e->pred_next)
8431 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8432 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8433 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
8435 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8436 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8437 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
8438 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
8439 BASIC_BLOCK (succ)));
8441 for (pred = 0; pred < n_basic_blocks; pred++)
8443 basic_block p = BASIC_BLOCK (pred);
8444 basic_block s = EXIT_BLOCK_PTR;
8448 for (e = p->succ; e; e = e->succ_next)
8454 for (e = s->pred; e; e = e->pred_next)
8460 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8461 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8462 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
8464 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8465 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8466 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
8467 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8472 /* This routine will determine what, if any, edge there is between
8473 a specified predecessor and successor. */
8476 find_edge_index (edge_list, pred, succ)
8477 struct edge_list *edge_list;
8478 basic_block pred, succ;
8481 for (x = 0; x < NUM_EDGES (edge_list); x++)
8483 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
8484 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
8487 return (EDGE_INDEX_NO_EDGE);
8490 /* This function will remove an edge from the flow graph. */
8496 edge last_pred = NULL;
8497 edge last_succ = NULL;
8499 basic_block src, dest;
8502 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
8508 last_succ->succ_next = e->succ_next;
8510 src->succ = e->succ_next;
8512 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
8518 last_pred->pred_next = e->pred_next;
8520 dest->pred = e->pred_next;
8526 /* This routine will remove any fake successor edges for a basic block.
8527 When the edge is removed, it is also removed from whatever predecessor
8531 remove_fake_successors (bb)
8535 for (e = bb->succ; e;)
8539 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
8544 /* This routine will remove all fake edges from the flow graph. If
8545 we remove all fake successors, it will automatically remove all
8546 fake predecessors. */
8549 remove_fake_edges ()
8553 for (x = 0; x < n_basic_blocks; x++)
8554 remove_fake_successors (BASIC_BLOCK (x));
8556 /* We've handled all successors except the entry block's. */
8557 remove_fake_successors (ENTRY_BLOCK_PTR);
8560 /* This function will add a fake edge between any block which has no
8561 successors, and the exit block. Some data flow equations require these
8565 add_noreturn_fake_exit_edges ()
8569 for (x = 0; x < n_basic_blocks; x++)
8570 if (BASIC_BLOCK (x)->succ == NULL)
8571 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
8574 /* This function adds a fake edge between any infinite loops to the
8575 exit block. Some optimizations require a path from each node to
8578 See also Morgan, Figure 3.10, pp. 82-83.
8580 The current implementation is ugly, not attempting to minimize the
8581 number of inserted fake edges. To reduce the number of fake edges
8582 to insert, add fake edges from _innermost_ loops containing only
8583 nodes not reachable from the exit block. */
8586 connect_infinite_loops_to_exit ()
8588 basic_block unvisited_block;
8590 /* Perform depth-first search in the reverse graph to find nodes
8591 reachable from the exit block. */
8592 struct depth_first_search_dsS dfs_ds;
8594 flow_dfs_compute_reverse_init (&dfs_ds);
8595 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
8597 /* Repeatedly add fake edges, updating the unreachable nodes. */
8600 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
8601 if (!unvisited_block)
8603 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
8604 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
8607 flow_dfs_compute_reverse_finish (&dfs_ds);
8612 /* Redirect an edge's successor from one block to another. */
8615 redirect_edge_succ (e, new_succ)
8617 basic_block new_succ;
8621 /* Disconnect the edge from the old successor block. */
8622 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
8624 *pe = (*pe)->pred_next;
8626 /* Reconnect the edge to the new successor block. */
8627 e->pred_next = new_succ->pred;
8632 /* Redirect an edge's predecessor from one block to another. */
8635 redirect_edge_pred (e, new_pred)
8637 basic_block new_pred;
8641 /* Disconnect the edge from the old predecessor block. */
8642 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
8644 *pe = (*pe)->succ_next;
8646 /* Reconnect the edge to the new predecessor block. */
8647 e->succ_next = new_pred->succ;
8652 /* Dump the list of basic blocks in the bitmap NODES. */
8655 flow_nodes_print (str, nodes, file)
8657 const sbitmap nodes;
8665 fprintf (file, "%s { ", str);
8666 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
8667 fputs ("}\n", file);
8671 /* Dump the list of edges in the array EDGE_LIST. */
8674 flow_edge_list_print (str, edge_list, num_edges, file)
8676 const edge *edge_list;
8685 fprintf (file, "%s { ", str);
8686 for (i = 0; i < num_edges; i++)
8687 fprintf (file, "%d->%d ", edge_list[i]->src->index,
8688 edge_list[i]->dest->index);
8689 fputs ("}\n", file);
8693 /* Dump loop related CFG information. */
8696 flow_loops_cfg_dump (loops, file)
8697 const struct loops *loops;
8702 if (! loops->num || ! file || ! loops->cfg.dom)
8705 for (i = 0; i < n_basic_blocks; i++)
8709 fprintf (file, ";; %d succs { ", i);
8710 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
8711 fprintf (file, "%d ", succ->dest->index);
8712 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
8715 /* Dump the DFS node order. */
8716 if (loops->cfg.dfs_order)
8718 fputs (";; DFS order: ", file);
8719 for (i = 0; i < n_basic_blocks; i++)
8720 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
8723 /* Dump the reverse completion node order. */
8724 if (loops->cfg.rc_order)
8726 fputs (";; RC order: ", file);
8727 for (i = 0; i < n_basic_blocks; i++)
8728 fprintf (file, "%d ", loops->cfg.rc_order[i]);
8733 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
8736 flow_loop_nested_p (outer, loop)
8740 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
8744 /* Dump the loop information specified by LOOP to the stream FILE
8745 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8747 flow_loop_dump (loop, file, loop_dump_aux, verbose)
8748 const struct loop *loop;
8750 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8753 if (! loop || ! loop->header)
8756 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
8757 loop->num, INSN_UID (loop->first->head),
8758 INSN_UID (loop->last->end),
8759 loop->shared ? " shared" : "",
8760 loop->invalid ? " invalid" : "");
8761 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
8762 loop->header->index, loop->latch->index,
8763 loop->pre_header ? loop->pre_header->index : -1,
8764 loop->first->index, loop->last->index);
8765 fprintf (file, ";; depth %d, level %d, outer %ld\n",
8766 loop->depth, loop->level,
8767 (long) (loop->outer ? loop->outer->num : -1));
8769 if (loop->pre_header_edges)
8770 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
8771 loop->num_pre_header_edges, file);
8772 flow_edge_list_print (";; entry edges", loop->entry_edges,
8773 loop->num_entries, file);
8774 fprintf (file, ";; %d", loop->num_nodes);
8775 flow_nodes_print (" nodes", loop->nodes, file);
8776 flow_edge_list_print (";; exit edges", loop->exit_edges,
8777 loop->num_exits, file);
8778 if (loop->exits_doms)
8779 flow_nodes_print (";; exit doms", loop->exits_doms, file);
8781 loop_dump_aux (loop, file, verbose);
8785 /* Dump the loop information specified by LOOPS to the stream FILE,
8786 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8788 flow_loops_dump (loops, file, loop_dump_aux, verbose)
8789 const struct loops *loops;
8791 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8797 num_loops = loops->num;
8798 if (! num_loops || ! file)
8801 fprintf (file, ";; %d loops found, %d levels\n",
8802 num_loops, loops->levels);
8804 for (i = 0; i < num_loops; i++)
8806 struct loop *loop = &loops->array[i];
8808 flow_loop_dump (loop, file, loop_dump_aux, verbose);
8814 for (j = 0; j < i; j++)
8816 struct loop *oloop = &loops->array[j];
8818 if (loop->header == oloop->header)
8823 smaller = loop->num_nodes < oloop->num_nodes;
8825 /* If the union of LOOP and OLOOP is different than
8826 the larger of LOOP and OLOOP then LOOP and OLOOP
8827 must be disjoint. */
8828 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
8829 smaller ? oloop : loop);
8831 ";; loop header %d shared by loops %d, %d %s\n",
8832 loop->header->index, i, j,
8833 disjoint ? "disjoint" : "nested");
8840 flow_loops_cfg_dump (loops, file);
8844 /* Free all the memory allocated for LOOPS. */
8847 flow_loops_free (loops)
8848 struct loops *loops;
8857 /* Free the loop descriptors. */
8858 for (i = 0; i < loops->num; i++)
8860 struct loop *loop = &loops->array[i];
8862 if (loop->pre_header_edges)
8863 free (loop->pre_header_edges);
8865 sbitmap_free (loop->nodes);
8866 if (loop->entry_edges)
8867 free (loop->entry_edges);
8868 if (loop->exit_edges)
8869 free (loop->exit_edges);
8870 if (loop->exits_doms)
8871 sbitmap_free (loop->exits_doms);
8873 free (loops->array);
8874 loops->array = NULL;
8877 sbitmap_vector_free (loops->cfg.dom);
8878 if (loops->cfg.dfs_order)
8879 free (loops->cfg.dfs_order);
8881 if (loops->shared_headers)
8882 sbitmap_free (loops->shared_headers);
8887 /* Find the entry edges into the loop with header HEADER and nodes
8888 NODES and store in ENTRY_EDGES array. Return the number of entry
8889 edges from the loop. */
8892 flow_loop_entry_edges_find (header, nodes, entry_edges)
8894 const sbitmap nodes;
8900 *entry_edges = NULL;
8903 for (e = header->pred; e; e = e->pred_next)
8905 basic_block src = e->src;
8907 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
8914 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
8917 for (e = header->pred; e; e = e->pred_next)
8919 basic_block src = e->src;
8921 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
8922 (*entry_edges)[num_entries++] = e;
8929 /* Find the exit edges from the loop using the bitmap of loop nodes
8930 NODES and store in EXIT_EDGES array. Return the number of
8931 exit edges from the loop. */
8934 flow_loop_exit_edges_find (nodes, exit_edges)
8935 const sbitmap nodes;
8944 /* Check all nodes within the loop to see if there are any
8945 successors not in the loop. Note that a node may have multiple
8946 exiting edges ????? A node can have one jumping edge and one fallthru
8947 edge so only one of these can exit the loop. */
8949 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
8950 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
8952 basic_block dest = e->dest;
8954 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
8962 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
8964 /* Store all exiting edges into an array. */
8966 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
8967 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
8969 basic_block dest = e->dest;
8971 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
8972 (*exit_edges)[num_exits++] = e;
8980 /* Find the nodes contained within the loop with header HEADER and
8981 latch LATCH and store in NODES. Return the number of nodes within
8985 flow_loop_nodes_find (header, latch, nodes)
8994 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
8997 /* Start with only the loop header in the set of loop nodes. */
8998 sbitmap_zero (nodes);
8999 SET_BIT (nodes, header->index);
9001 header->loop_depth++;
9003 /* Push the loop latch on to the stack. */
9004 if (! TEST_BIT (nodes, latch->index))
9006 SET_BIT (nodes, latch->index);
9007 latch->loop_depth++;
9009 stack[sp++] = latch;
9018 for (e = node->pred; e; e = e->pred_next)
9020 basic_block ancestor = e->src;
9022 /* If each ancestor not marked as part of loop, add to set of
9023 loop nodes and push on to stack. */
9024 if (ancestor != ENTRY_BLOCK_PTR
9025 && ! TEST_BIT (nodes, ancestor->index))
9027 SET_BIT (nodes, ancestor->index);
9028 ancestor->loop_depth++;
9030 stack[sp++] = ancestor;
9038 /* Compute the depth first search order and store in the array
9039 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
9040 RC_ORDER is non-zero, return the reverse completion number for each
9041 node. Returns the number of nodes visited. A depth first search
9042 tries to get as far away from the starting point as quickly as
9046 flow_depth_first_order_compute (dfs_order, rc_order)
9053 int rcnum = n_basic_blocks - 1;
9056 /* Allocate stack for back-tracking up CFG. */
9057 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
9060 /* Allocate bitmap to track nodes that have been visited. */
9061 visited = sbitmap_alloc (n_basic_blocks);
9063 /* None of the nodes in the CFG have been visited yet. */
9064 sbitmap_zero (visited);
9066 /* Push the first edge on to the stack. */
9067 stack[sp++] = ENTRY_BLOCK_PTR->succ;
9075 /* Look at the edge on the top of the stack. */
9080 /* Check if the edge destination has been visited yet. */
9081 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
9083 /* Mark that we have visited the destination. */
9084 SET_BIT (visited, dest->index);
9087 dfs_order[dfsnum++] = dest->index;
9091 /* Since the DEST node has been visited for the first
9092 time, check its successors. */
9093 stack[sp++] = dest->succ;
9097 /* There are no successors for the DEST node so assign
9098 its reverse completion number. */
9100 rc_order[rcnum--] = dest->index;
9105 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
9107 /* There are no more successors for the SRC node
9108 so assign its reverse completion number. */
9110 rc_order[rcnum--] = src->index;
9114 stack[sp - 1] = e->succ_next;
9121 sbitmap_free (visited);
9123 /* The number of nodes visited should not be greater than
9125 if (dfsnum > n_basic_blocks)
9128 /* There are some nodes left in the CFG that are unreachable. */
9129 if (dfsnum < n_basic_blocks)
9134 /* Compute the depth first search order on the _reverse_ graph and
9135 store in the array DFS_ORDER, marking the nodes visited in VISITED.
9136 Returns the number of nodes visited.
9138 The computation is split into three pieces:
9140 flow_dfs_compute_reverse_init () creates the necessary data
9143 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
9144 structures. The block will start the search.
9146 flow_dfs_compute_reverse_execute () continues (or starts) the
9147 search using the block on the top of the stack, stopping when the
9150 flow_dfs_compute_reverse_finish () destroys the necessary data
9153 Thus, the user will probably call ..._init(), call ..._add_bb() to
9154 add a beginning basic block to the stack, call ..._execute(),
9155 possibly add another bb to the stack and again call ..._execute(),
9156 ..., and finally call _finish(). */
9158 /* Initialize the data structures used for depth-first search on the
9159 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
9160 added to the basic block stack. DATA is the current depth-first
9161 search context. If INITIALIZE_STACK is non-zero, there is an
9162 element on the stack. */
9165 flow_dfs_compute_reverse_init (data)
9166 depth_first_search_ds data;
9168 /* Allocate stack for back-tracking up CFG. */
9170 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
9171 * sizeof (basic_block));
9174 /* Allocate bitmap to track nodes that have been visited. */
9175 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
9177 /* None of the nodes in the CFG have been visited yet. */
9178 sbitmap_zero (data->visited_blocks);
9183 /* Add the specified basic block to the top of the dfs data
9184 structures. When the search continues, it will start at the
9188 flow_dfs_compute_reverse_add_bb (data, bb)
9189 depth_first_search_ds data;
9192 data->stack[data->sp++] = bb;
9196 /* Continue the depth-first search through the reverse graph starting
9197 with the block at the stack's top and ending when the stack is
9198 empty. Visited nodes are marked. Returns an unvisited basic
9199 block, or NULL if there is none available. */
9202 flow_dfs_compute_reverse_execute (data)
9203 depth_first_search_ds data;
9209 while (data->sp > 0)
9211 bb = data->stack[--data->sp];
9213 /* Mark that we have visited this node. */
9214 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
9216 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
9218 /* Perform depth-first search on adjacent vertices. */
9219 for (e = bb->pred; e; e = e->pred_next)
9220 flow_dfs_compute_reverse_add_bb (data, e->src);
9224 /* Determine if there are unvisited basic blocks. */
9225 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
9226 if (!TEST_BIT (data->visited_blocks, i))
9227 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
9231 /* Destroy the data structures needed for depth-first search on the
9235 flow_dfs_compute_reverse_finish (data)
9236 depth_first_search_ds data;
9239 sbitmap_free (data->visited_blocks);
9244 /* Find the root node of the loop pre-header extended basic block and
9245 the edges along the trace from the root node to the loop header. */
9248 flow_loop_pre_header_scan (loop)
9254 loop->num_pre_header_edges = 0;
9256 if (loop->num_entries != 1)
9259 ebb = loop->entry_edges[0]->src;
9261 if (ebb != ENTRY_BLOCK_PTR)
9265 /* Count number of edges along trace from loop header to
9266 root of pre-header extended basic block. Usually this is
9267 only one or two edges. */
9269 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
9271 ebb = ebb->pred->src;
9275 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
9276 loop->num_pre_header_edges = num;
9278 /* Store edges in order that they are followed. The source
9279 of the first edge is the root node of the pre-header extended
9280 basic block and the destination of the last last edge is
9282 for (e = loop->entry_edges[0]; num; e = e->src->pred)
9284 loop->pre_header_edges[--num] = e;
9290 /* Return the block for the pre-header of the loop with header
9291 HEADER where DOM specifies the dominator information. Return NULL if
9292 there is no pre-header. */
9295 flow_loop_pre_header_find (header, dom)
9299 basic_block pre_header;
9302 /* If block p is a predecessor of the header and is the only block
9303 that the header does not dominate, then it is the pre-header. */
9305 for (e = header->pred; e; e = e->pred_next)
9307 basic_block node = e->src;
9309 if (node != ENTRY_BLOCK_PTR
9310 && ! TEST_BIT (dom[node->index], header->index))
9312 if (pre_header == NULL)
9316 /* There are multiple edges into the header from outside
9317 the loop so there is no pre-header block. */
9326 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
9327 previously added. The insertion algorithm assumes that the loops
9328 are added in the order found by a depth first search of the CFG. */
9331 flow_loop_tree_node_add (prevloop, loop)
9332 struct loop *prevloop;
9336 if (flow_loop_nested_p (prevloop, loop))
9338 prevloop->inner = loop;
9339 loop->outer = prevloop;
9343 while (prevloop->outer)
9345 if (flow_loop_nested_p (prevloop->outer, loop))
9347 prevloop->next = loop;
9348 loop->outer = prevloop->outer;
9351 prevloop = prevloop->outer;
9354 prevloop->next = loop;
9358 /* Build the loop hierarchy tree for LOOPS. */
9361 flow_loops_tree_build (loops)
9362 struct loops *loops;
9367 num_loops = loops->num;
9371 /* Root the loop hierarchy tree with the first loop found.
9372 Since we used a depth first search this should be the
9374 loops->tree_root = &loops->array[0];
9375 loops->tree_root->outer = loops->tree_root->inner = loops->tree_root->next = NULL;
9377 /* Add the remaining loops to the tree. */
9378 for (i = 1; i < num_loops; i++)
9379 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
9382 /* Helper function to compute loop nesting depth and enclosed loop level
9383 for the natural loop specified by LOOP at the loop depth DEPTH.
9384 Returns the loop level. */
9387 flow_loop_level_compute (loop, depth)
9397 /* Traverse loop tree assigning depth and computing level as the
9398 maximum level of all the inner loops of this loop. The loop
9399 level is equivalent to the height of the loop in the loop tree
9400 and corresponds to the number of enclosed loop levels (including
9402 for (inner = loop->inner; inner; inner = inner->next)
9406 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
9411 loop->level = level;
9412 loop->depth = depth;
9416 /* Compute the loop nesting depth and enclosed loop level for the loop
9417 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
9421 flow_loops_level_compute (loops)
9422 struct loops *loops;
9428 /* Traverse all the outer level loops. */
9429 for (loop = loops->tree_root; loop; loop = loop->next)
9431 level = flow_loop_level_compute (loop, 1);
9439 /* Scan a single natural loop specified by LOOP collecting information
9440 about it specified by FLAGS. */
9443 flow_loop_scan (loops, loop, flags)
9444 struct loops *loops;
9448 /* Determine prerequisites. */
9449 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
9450 flags |= LOOP_EXIT_EDGES;
9452 if (flags & LOOP_ENTRY_EDGES)
9454 /* Find edges which enter the loop header.
9455 Note that the entry edges should only
9456 enter the header of a natural loop. */
9458 = flow_loop_entry_edges_find (loop->header,
9460 &loop->entry_edges);
9463 if (flags & LOOP_EXIT_EDGES)
9465 /* Find edges which exit the loop. */
9467 = flow_loop_exit_edges_find (loop->nodes,
9471 if (flags & LOOP_EXITS_DOMS)
9475 /* Determine which loop nodes dominate all the exits
9477 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
9478 sbitmap_copy (loop->exits_doms, loop->nodes);
9479 for (j = 0; j < loop->num_exits; j++)
9480 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
9481 loops->cfg.dom[loop->exit_edges[j]->src->index]);
9483 /* The header of a natural loop must dominate
9485 if (! TEST_BIT (loop->exits_doms, loop->header->index))
9489 if (flags & LOOP_PRE_HEADER)
9491 /* Look to see if the loop has a pre-header node. */
9493 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
9495 /* Find the blocks within the extended basic block of
9496 the loop pre-header. */
9497 flow_loop_pre_header_scan (loop);
9503 /* Find all the natural loops in the function and save in LOOPS structure
9504 and recalculate loop_depth information in basic block structures.
9505 FLAGS controls which loop information is collected.
9506 Return the number of natural loops found. */
9509 flow_loops_find (loops, flags)
9510 struct loops *loops;
9522 /* This function cannot be repeatedly called with different
9523 flags to build up the loop information. The loop tree
9524 must always be built if this function is called. */
9525 if (! (flags & LOOP_TREE))
9528 memset (loops, 0, sizeof (*loops));
9530 /* Taking care of this degenerate case makes the rest of
9531 this code simpler. */
9532 if (n_basic_blocks == 0)
9538 /* Compute the dominators. */
9539 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
9540 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
9542 /* Count the number of loop edges (back edges). This should be the
9543 same as the number of natural loops. */
9546 for (b = 0; b < n_basic_blocks; b++)
9550 header = BASIC_BLOCK (b);
9551 header->loop_depth = 0;
9553 for (e = header->pred; e; e = e->pred_next)
9555 basic_block latch = e->src;
9557 /* Look for back edges where a predecessor is dominated
9558 by this block. A natural loop has a single entry
9559 node (header) that dominates all the nodes in the
9560 loop. It also has single back edge to the header
9561 from a latch node. Note that multiple natural loops
9562 may share the same header. */
9563 if (b != header->index)
9566 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
9573 /* Compute depth first search order of the CFG so that outer
9574 natural loops will be found before inner natural loops. */
9575 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9576 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9577 flow_depth_first_order_compute (dfs_order, rc_order);
9579 /* Save CFG derived information to avoid recomputing it. */
9580 loops->cfg.dom = dom;
9581 loops->cfg.dfs_order = dfs_order;
9582 loops->cfg.rc_order = rc_order;
9584 /* Allocate loop structures. */
9586 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
9588 headers = sbitmap_alloc (n_basic_blocks);
9589 sbitmap_zero (headers);
9591 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
9592 sbitmap_zero (loops->shared_headers);
9594 /* Find and record information about all the natural loops
9597 for (b = 0; b < n_basic_blocks; b++)
9601 /* Search the nodes of the CFG in reverse completion order
9602 so that we can find outer loops first. */
9603 header = BASIC_BLOCK (rc_order[b]);
9605 /* Look for all the possible latch blocks for this header. */
9606 for (e = header->pred; e; e = e->pred_next)
9608 basic_block latch = e->src;
9610 /* Look for back edges where a predecessor is dominated
9611 by this block. A natural loop has a single entry
9612 node (header) that dominates all the nodes in the
9613 loop. It also has single back edge to the header
9614 from a latch node. Note that multiple natural loops
9615 may share the same header. */
9616 if (latch != ENTRY_BLOCK_PTR
9617 && TEST_BIT (dom[latch->index], header->index))
9621 loop = loops->array + num_loops;
9623 loop->header = header;
9624 loop->latch = latch;
9625 loop->num = num_loops;
9632 for (i = 0; i < num_loops; i++)
9634 struct loop *loop = &loops->array[i];
9636 /* Keep track of blocks that are loop headers so
9637 that we can tell which loops should be merged. */
9638 if (TEST_BIT (headers, loop->header->index))
9639 SET_BIT (loops->shared_headers, loop->header->index);
9640 SET_BIT (headers, loop->header->index);
9642 /* Find nodes contained within the loop. */
9643 loop->nodes = sbitmap_alloc (n_basic_blocks);
9645 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
9647 /* Compute first and last blocks within the loop.
9648 These are often the same as the loop header and
9649 loop latch respectively, but this is not always
9652 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
9654 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
9656 flow_loop_scan (loops, loop, flags);
9659 /* Natural loops with shared headers may either be disjoint or
9660 nested. Disjoint loops with shared headers cannot be inner
9661 loops and should be merged. For now just mark loops that share
9663 for (i = 0; i < num_loops; i++)
9664 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
9665 loops->array[i].shared = 1;
9667 sbitmap_free (headers);
9671 sbitmap_vector_free (dom);
9674 loops->num = num_loops;
9676 /* Build the loop hierarchy tree. */
9677 flow_loops_tree_build (loops);
9679 /* Assign the loop nesting depth and enclosed loop level for each
9681 loops->levels = flow_loops_level_compute (loops);
9687 /* Update the information regarding the loops in the CFG
9688 specified by LOOPS. */
9690 flow_loops_update (loops, flags)
9691 struct loops *loops;
9694 /* One day we may want to update the current loop data. For now
9695 throw away the old stuff and rebuild what we need. */
9697 flow_loops_free (loops);
9699 return flow_loops_find (loops, flags);
9703 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
9706 flow_loop_outside_edge_p (loop, e)
9707 const struct loop *loop;
9710 if (e->dest != loop->header)
9712 return (e->src == ENTRY_BLOCK_PTR)
9713 || ! TEST_BIT (loop->nodes, e->src->index);
9716 /* Clear LOG_LINKS fields of insns in a chain.
9717 Also clear the global_live_at_{start,end} fields of the basic block
9721 clear_log_links (insns)
9727 for (i = insns; i; i = NEXT_INSN (i))
9731 for (b = 0; b < n_basic_blocks; b++)
9733 basic_block bb = BASIC_BLOCK (b);
9735 bb->global_live_at_start = NULL;
9736 bb->global_live_at_end = NULL;
9739 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
9740 EXIT_BLOCK_PTR->global_live_at_start = NULL;
9743 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
9744 correspond to the hard registers, if any, set in that map. This
9745 could be done far more efficiently by having all sorts of special-cases
9746 with moving single words, but probably isn't worth the trouble. */
9749 reg_set_to_hard_reg_set (to, from)
9755 EXECUTE_IF_SET_IN_BITMAP
9758 if (i >= FIRST_PSEUDO_REGISTER)
9760 SET_HARD_REG_BIT (*to, i);
9764 /* Called once at intialization time. */
9769 static int initialized;
9773 gcc_obstack_init (&flow_obstack);
9774 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
9779 obstack_free (&flow_obstack, flow_firstobj);
9780 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
9784 /* Assume that the preceeding pass has possibly eliminated jump instructions
9785 or converted the unconditional jumps. Eliminate the edges from CFG. */
9788 purge_dead_edges (bb)
9793 if (GET_CODE (insn) == JUMP_INSN && !simplejump_p (insn))
9795 if (GET_CODE (insn) == JUMP_INSN)
9797 for (e = bb->succ; e; e = next)
9799 next = e->succ_next;
9800 if (e->dest == EXIT_BLOCK_PTR || e->dest->head != JUMP_LABEL (insn))
9803 if (bb->succ && bb->succ->succ_next)
9807 bb->succ->probability = REG_BR_PROB_BASE;
9808 bb->succ->count = bb->count;
9811 fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
9814 /* If we don't see a jump insn, we don't know exactly why the block would
9815 have been broken at this point. Look for a simple, non-fallthru edge,
9816 as these are only created by conditional branches. If we find such an
9817 edge we know that there used to be a jump here and can then safely
9818 remove all non-fallthru edges. */
9819 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
9823 for (e = bb->succ; e; e = next)
9825 next = e->succ_next;
9826 if (!(e->flags & EDGE_FALLTHRU))
9829 if (!bb->succ || bb->succ->succ_next)
9831 bb->succ->probability = REG_BR_PROB_BASE;
9832 bb->succ->count = bb->count;
9835 fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n",
9840 /* Search all basic blocks for potentionally dead edges and purge them. */
9843 purge_all_dead_edges ()
9846 for (i = 0; i < n_basic_blocks; i++)
9847 purge_dead_edges (BASIC_BLOCK (i));